cardamom and spent coffee crumb cake
a plush, buttery cake flecked with spent coffee grounds
who doesn’t love a good crumb cake? they’re hefty and humble, moist and buttery, simple and delicious. there are lots of versions of the original new york (or new jersey?) style crumb cake which features a soft, sour cream enriched cake base topped with a lot, and i mean a lot, of brown sugar and cinnamon crumbs. for this take, i was aiming for that same plush cake with a different flavor and look.
inspired by a spent coffee cookie a former colleague and friend of mine developed (hi chiara!), i prepared some used coffee grounds (the process for that is detailed below) and decided to pair it with crushed cardamom throughout. i also used brown butter for the crumb, which is a super easy swap you can easily make for any crumb cake to add a richer, nuttier flavor without too much extra effort. the final product is a moist, cardamom forward cake with plenty of sweet-salty crumbs and a mild coffee flavor that gently tempers its buttery sweetness.
i call for crushed cardamom as opposed to ground cardamom because i simply prefer the bigger hits of cardamom flavor you get when you crunch into a crushed seed; you just can’t replicate that with the ground stuff. to make crushed cardamom: break the seeds out of the papery shells of whole green cardamom pods—this takes some time and hands on effort. blitz the seeds a second or two in a spice grinder, pound in a mortar and pestle or crush with the side of a chef’s knife until broken up but not powdery or fine.
there are recipes that call for freshly used grounds, which you can certainly use here, but i prefer to dry them first to control the amount of liquid in the recipe and be able to keep them in the fridge for future use. how to prepare spent coffee: spread freshly used coffee grounds (i use grounds directly from my filter coffee machine which i grind at home just before making coffee) on a parchment lined baking sheet in as even a layer as possible, breaking up any clumps, and bake for 30 minutes at 100°C/200°F. the grounds should be completely dry and sandy with no clumps. if not, toss them around and keep baking in 15 minute increments until they’re completely dry; if the grounds are not completely dry, they will mold. let cool completely then store in an airtight container in the fridge for up to 1 month.
makes one 23 cm / 9-inch round or 8-inch square cake; this recipe is an adaptation of smitten kitchen’s new york crumb cake
for the crumb
140 grams unsalted butter
1 tablespoon milk powder (optional)
1 tablespoon spent coffee grounds (dried as outlined above or freshly used)
1 teaspoon crushed cardamom (or 1/2 teaspoon ground cardamom)
100 grams brown sugar
50 grams granulated sugar
1/4 teaspoon salt
215 grams all-purpose flour
for the cake
85 grams unsalted butter (room temperature)
100 grams granulated sugar
1 large egg
150 grams sour cream
1 tsp vanilla extract
1 1/4 tsp baking powder
3/4 tsp salt
1 teaspoon crushed cardamom (or 1/2 teaspoon ground cardamom)
1 tablespoon spent coffee grounds (dried as outlined above or freshly used)
130 grams all-purpose flour
preheat the oven to 175°C/350°F. lightly coat a cake pan with some butter (i like to save my butter wrappers in the freezer and use them for this purpose!) and line with parchment paper.
to make the crumb, add butter to a small frying pan (preferably stainless steel or light bottomed pan so you can see the milk solids browning) over medium heat. let melt, then froth, swirling occasionally. once the butter has frothed, add the milk powder and swirl to combine. the milk solids will start to sink and turn deep golden brown so keep a close eye on it, swirling or stirring often; the whole process should take about 10 minutes. remove from the heat and transfer to a large bowl. stir in the spent coffee grounds and crushed cardamom and let cool for about 10 minutes. add sugars, salt and flour and mix just until the flour disappears; it should be quite thick. set aside.
to make the cake, add butter and sugar to a stand mixer with the paddle attachment and beat until pale and fluffy; you can also use a hand mixer with beaters. add the egg, sour cream and vanilla extract and beat until well combined. add baking powder, salt, crushed cardamom, spent coffee grounds and flour and mix on low speed just until the flour disappears.
transfer the cake batter to the prepared pan and smooth out the surface. use clean hands to take large pieces of the crumb topping, squishing the mixture together and then breaking it up into irregular crumbles all over the surface of the batter. bake for about 35 minutes, or until a toothpick or knife inserted into the center of the cake comes out clean.
let cool for at least 15 minutes before removing from the cake pan with the help of the parchment paper, slicing and serving. the cake will keep for up to 5 days in an airtight container or wrapped tightly in plastic at room temperature.