Cardamom and Tea

Almost all rhubarb cookies treat chunks of rhubarb as if they are chocolate chips, mixing them into the dough and calling it a day. This might yield an okay cookie, but I think we can do better. After all, bits of rhubarb aren’t anything like chocolate chips—let’s not expect them to be.

By spending a quick 15 minutes turning our rhubarb into a 2-ingredient jam, we end up with a very intentional cookie that tastes rhubarby as heck. And as an added bonus, these rhubarb thumbprints look gorgeous, with little pools of deep pink jam in the center of a soft and chewy vanilla cookie.

Jam-making might seem intimidating or time consuming, but my rhubarb jam recipe yields a nice little batch, with enough for these cookies + a bit leftover for the fridge. Small batches of jam are simple to throw together, and they take very little time to cook down.

If you’re picturing the stockpots of jam your grandmother made every summer, this is not that. This one is for everyone, even folks who are totally new to jam making. You need no special equipment or special ingredients, just a spare 15 minutes.

Jump to the recipe to hit the ground running, or read on for a bit more context.

Making jam (or, the most impressive thing you can do with 15 minutes)

Jam, at its simplest, is just simmering fruit and sugar together until you’ve cooked off enough water that it sets. Sure, diehard jam makers use specialized ingredients and equipment like pectin, candy-making thermometers, and even sometimes digital pH meters—but those are absolutely irrelevant to this cookie recipe.

For the jam in this recipe, you just need a wide pan/pot, 1 bunch of rhubarb, sugar, salt, and water. You basically place all those ingredients together, bring to a simmer, and reduce down until it reaches the right consistency. Follow my rhubarb jam recipe and you can’t go wrong. It has a video, a step-by-step recipe, and helpful, fail-proof tips.

Here’s a quick video (but check out the post for the actual step-by-step recipe):

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A few notes on these rhubarb cookies

No chemical leavening agents (so really cream that sugar and butter!)

These cookies have no chemical leavening agents (like baking powder or soda), which is a good thing. Chemical leavening agents would cause our cookies to puff up too much in the oven, which would make the jam run over the sides.

However, this means you need to take the sugar/butter creaming step seriously. That’s the one time we incorporate air into the cookies, and it allows for just enough to make them taste light and fluffy without puffing up too much.

Less sugar = more room for jam

The ingredient ratios include less sugar than your average cookie recipe, which means the jam on top doesn’t make it overly sweet. It might seem like not enough sugar, but it’s just the right amount.

Where this recipe comes from

I typically develop my own recipes, rather than curating and/or adapting recipes from other sources. But when I decided to make a rhubarb cookie recipe, I knew I had to adapt Recipe Tin Eats‘ recipe for jam drops, which is my go-to thumbprint cookie recipe. It’s simply the GOAT. The cookies are soft and chewy (rather than shortbready) and the shaping technique is easy and fail-proof.

I’ve changed Nagi’s recipe slightly, first to include rhubarb jam in particular (obviously), but also:

I rewrote the instructions in my own words and changed the method slightly.
I decided to make the cookies a bit bigger (and thus a slightly longer bake time).
I use granulated instead of caster sugar and upped the salt a bit.
I shifted one of the volume/weight quantities to better reflect my own conversion chart (which I’ve spent years perfecting, and which I think yields very good results for both volume and weight baking). As with any baking recipe, you’ll get more consistent results with weight measurements, but volume works fine if you don’t have a scale.

Rhubarb Cookies

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This recipe is adapted from Recipe Tin Eats’ jam drops.

Yield: 40 cookies

Ingredients

2 sticks (225g) unsalted butter
3/4 cup (150g) granulated sugar
1/2 tsp salt
1 large egg
2 tsp vanilla extract
2 3/4 cups (375g) all purpose flour
1/2 cup (160g) rhubarb jam,* cooled and well-stirred

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Instructions

Preheat the oven to 350°F (180°C). Line 2 baking sheets with parchment paper.
Place the butter, sugar, and salt in the bowl of a stand mixer fitted with the paddle attachment. Beat together at medium-high speed until very light and fluffy, about 2 minutes.
Add the egg and vanilla and continue mixing until very light and fluffy, about 30 more seconds. Scrape down the sides and bottom of the bowl with a flexible spatula and beat for a few more seconds to combine.
Add the flour and mix together at low speed, just until it forms a uniform dough (about 15 to 30 seconds). Scrape the bottom of the bowl to make sure it is fully incorporated, but do not over-mix.
Measure out 1 slightly heaped Tbsp (20g or #50 disher) balls. Roll smooth and make a thumbprint with the ball cupped in your hand to avoid cracks.
Place each thumb-printed disc on the baking sheet with an inch or two between each one. Fill each one with 1/2 tsp jam (do not go over the level of the cookie).
Bake for 15 minutes, letting them fully cool on the tray.

Notes

* My rhubarb jam recipe is really easy and makes a small batch (enough for this recipe with a nice little bit left over for the fridge). Check out the full post if you’ve never made jam, but here’s a quick recipe for reference:

Rhubarb jam:

1 Tbsp water
3 cups [300 g] sliced rhubarb
1/8 tsp salt
1 1/4 cups [250 g] granulated sugar

Place a plate in the freezer (you’ll need it to test the jam later).
Place the water, rhubarb, salt, and sugar (in that order) in a wide pot or pan over medium heat—do not stir it! Once it starts making a sizzling sound, let it simmer away for about 3 minutes (still no stirring), until liquid starts collecting on the bottom. At that point, give it a stir.
Control the heat to maintain a rapid simmer, and cook stirring occasionally for about 12 more minutes. The amount of time will vary. Wider-mouth pots and pans take less time than narrow pots and pans, and higher heat will also speed up the process.
Once the jam has visibly thickened and become much less foamy, start testing it for doneness. Drop a little bit on the frozen plate and see if it sets. Nudge it around the plate a bit to make sure it fully chills, and inspect its texture. Whatever texture it is on the plate is the texture it will be in the fridge, so use that information as you’d like.

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This rhubarb jam recipe makes a pretty small batch, but it’s easy to scale up as needed. However, unless you are the proud owner of a super productive rhubarb garden, I highly recommend sticking to the smaller amount. After all, smaller batches of jam come together much more quickly than large batches. Why is that?

Well, jam-making is all about boiling off moisture from the fruit. With a larger vat of jam, you have to let it bubble away for much longer to get enough water to evaporate (sometimes as long as an hour!). I’d personally much rather just spend a quick 15 minutes whipping up a jar every once in a while.

But it’s your call! This recipe has you covered whether you want to make enough for the whole neighborhood or enough for that little gap in your fridge door.

Jump to the recipe to hit the ground running, or read on for a few helpful jam tips (and check out my other rhubarb recipes, including rhubarb cookies featuring this very jam):

Rhubarb jam best practices

1) Don’t add much water

Some recipes for jam suggest adding several cups of water at the beginning of the process. I can almost get behind the idea—a bit of water helps the fruit soften faster and start to break down. However, as we know, the whole point of jam-making is to cook off as much water as possible. Adding a ton of water in the beginning is just setting us up for a needlessly long process.

Instead of starting the jam totally dry on the stove, I use the following technique instead:

Add 1 Tbsp of water to the bottom of the pot, followed by the fruit and sugar. Then without stirring, let it simmer for a few minutes. The water gets things going without adding much moisture. If you were to stir it before things start simmering, the sugar will start to grab onto some of that water, slowing things down a bit.

rhubarb jam simmering in a pan, early in the process with foam on top

rhubarb jam simmering in a pan, thickened with spatula dragged across bottom

2) Use a wide pot or pan

The wider the pot/pan, the faster your jam will cook. If you use a super narrow saucepan, it will take longer for water to cook off. Surface area is your friend. Use a wide skillet, dutch oven, or other pan with a nice amount of floorspace.

3) Most “freezer plate” advice is slightly wrong

The freezer plate method of checking jam doneness is fantastic, but I think most people get it like 5% wrong (and unfortunately, it’s the most important 5%).

Most videos/recipes will tell you to place a blob of jam on a frozen plate, and then drag your finger across it. According to these guides, if it doesn’t fill back in, it’s done. But this is unfortunately not a reliable cue. Even if your jam is quite underdone, it will often pass this test.

Instead, move the blob of jam around the plate a bit with your finger or a spoon to fully chill it and judge its consistency. Once chilled, does it have a thick, sticky consistency? Or does it feel more like a syrup than a jam? Would you spread that blob on toast, or would you drizzle it into an old fashioned?

4) Scale the sugar up slightly if you want it to keep longer

I love my jam sweet, but not so sugary that it waters down the flavor of the fruit. But, unfortunately, a sweeter jam will keep longer in the fridge.

Traditional recipes usually go for a 1:1 ratio of fruit to sugar (by weight). So for this amount of rhubarb (300g), that would be 1 1/2 sugar (300g)—1/4 cup more.

I personally prefer the flavor of this recipe’s ratio, which is by no means low-sugar, but if you want your rhubarb jam to last longer than a couple weeks, you might wish to go with the full amount of sugar. Discard if it starts to grow mold (mold has roots!), smells like alcohol, or starts to look slimy.

I prefer storing anything I don’t plan to use in the next week or two in the freezer, moving to the fridge as needed. I usually split this recipe in half, storing a small jar in the freezer and a small jar in the fridge.