Prep the pan and oven. Preheat your oven to 350°F (175°C). Grease a 9-inch springform pan or line a 9-inch round cake pan with parchment. Lightly butter the sides to prevent sticking.

Mix the dry ingredients. In a medium bowl, whisk together 2 cups almond flour, 2 tablespoons coconut flour, 1 cup granulated keto sweetener, 2 teaspoons baking powder, and 1/4 teaspoon salt. Break up any clumps for a smooth batter later.

Combine the wet ingredients. In a large bowl, whisk 1 1/2 cups full-fat ricotta until creamy. Add 4 large eggs, one at a time, whisking until smooth. Stir in 1/2 cup melted butter, 2 teaspoons vanilla extract, the zest of 2 lemons, and 2–3 tablespoons fresh lemon juice. For extra lemon flavor, add 1/4 teaspoon lemon extract.

Bring it together. Add the dry ingredients to the wet and stir until just combined. The batter should be thick but spreadable. If it looks too stiff, add 1 tablespoon more lemon juice or a splash of almond milk.

Fill the pan. Spread the batter evenly in the prepared pan. Smooth the top with a spatula so it bakes evenly.

Bake. Bake for 35–45 minutes, until the top is golden and a toothpick inserted near the center comes out clean or with a few moist crumbs. If the top browns too quickly, tent lightly with foil during the last 10 minutes.

Cool. Let the cake cool in the pan for 15 minutes, then run a knife around the edges and release from the pan. Cool completely on a rack. This helps set the crumb.

Finish and serve. Dust with powdered keto sweetener if you like. Slice and serve as is, or with a spoonful of lightly sweetened whipped cream and extra lemon zest.