Prep the pan and oven: Preheat oven to 350°F (175°C).
Grease and line an 8-inch round cake pan or a 9-inch springform with parchment.
Mix dry ingredients: In a large bowl, whisk almond flour, coconut flour, baking powder, salt, and sweetener until no lumps remain.
Combine wet ingredients: In another bowl, whisk eggs, melted butter, almond milk, vanilla, and almond extract until smooth.
Make the batter: Pour wet ingredients into the dry. Stir with a spatula until just combined. The batter should be thick but spreadable.
Pan and top: Spread batter evenly in the pan.
If using, sprinkle sliced almonds on top for texture and a light crunch.
Bake: Bake 28–35 minutes, or until the top is golden and a toothpick comes out mostly clean with a few moist crumbs.
Cool properly: Let the cake cool in the pan for 10 minutes, then transfer to a wire rack to finish cooling. Don’t frost or slice while hot.
Serve: Dust with powdered keto sweetener, add fresh berries, or top with lightly sweetened whipped cream.