Ingredients
Scale
For the Cake:
- 1 1/2 cups (188 grams) all-purpose flour
- 1 teaspoon baking powder
- 1/2 teaspoon ground coriander
- 3/4 teaspoon kosher salt
- 1/4 teaspoon baking soda
- 1/2 cup (1 stick,113 grams) unsalted butter, at room temperature
- 2/3 cup (133 grams) granulated sugar
- 2 large eggs, at room temperature
- 1 teaspoon vanilla extract or vanilla bean paste
- 3/4 cup (184 grams) sour cream, at room temperature
- About 1 cup store-bought lemon curd (8–10 ounces jar would be perfect!)
For the Crumble:
- 1/2 cup (64 grams) all-purpose flour
- 1/2 cup (45 grams) old-fashioned oats
- 1/2 cup (100 grams0 granulated sugar
- large pinch of salt
- 4 tablespoons (56 grams) cold unsalted butter, cut into small chunks
- Powdered sugar for topping
Instructions
- Place a rack in the upper third of the oven and preheat oven to 350 degrees F. Grease a 9-inch round baking pan (or springform pan), line the bottom with a circle of parchment paper and grease the parchment paper as well. Lightly flour the pan and knock any extra flour from the pan.
- In a small bowl whisk together flour, baking powder, coriander if using, salt, and baking soda. Set aside.
- In a large bowl with electric hand beaters or the bowl of a stand mixer fitted with a paddle attachment, beat together butter and sugar on medium speed until pale and fluffy, 3 to 5 minutes. Beat in the eggs, one at a time, beating for 1 minute per egg. Beat in the vanilla extract.
- Stop the mixer and scrape down the sides of the bowl to ensure that everything is mixed in well. Beat in the sour cream on medium speed.
- Turn the mixer to low and add the dry ingredients, mixing until just combined. Stop the mixer and finish incorporating the batter until well combined. The batter will be thick.
- To make the oat crumble, in a medium bowl, whisk together flour, oats, sugar, and salt. Add the cold butter chunks and, using your fingers, work the butter into the flour mixture. Quickly break the butter down into the mixture until well incorporated. Some butter bits will be the size of small peas and oat flakes.
- Spread half of the cake batter into the bottom of the prepared pan. An offset spatula is a great tool to spread the batter. Dollop with half of the lemon curd and sprinkle with just under half of the oat crumble. Lightly swirl the batter. Top with the remaining cake batter, spreading to the edges. Dollop with the remaining lemon curd and sprinkle with remaining crumble. Lightly swirl, leaving generous dollops of curd exposed on the top of the cake. They’ll bake to irresistibly jammy. Bake until deeply golden and the sides of the cake are pulling away from the pan. A toothpick inserted in the cake will come out clean or with just a few moist crumbs. This is a long bake cake at 45-55 minutes. Rotate the pan halfway through baking. Remove cake from the oven and allow to rest for 20 to 30 minutes before trying to invert the cake.
- Run a knife around the inside edge of the pan to loosen the cake from the pan. Place a flat plate over the pan and invert the cake. Peel the parchment round off the cake and gently invert the cake top side up.
- Serve warm or at room temperature lightly dusted with powdered sugar. Cake lasts, wrapped in the refrigerator, for up to 4 days.