In a small saucepan over medium heat, melt ½ cup (113g) unsalted butter. Cook, stirring occasionally, until the butter foams and the milk solids turn golden brown with a nutty aroma. Pour into a bowl and let cool for 10–15 minutes.

In the same saucepan, melt 4 tablespoons (56g) butter over medium heat. Cook until the butter turns golden brown and fragrant. Remove from heat.

In a bowl combine ¾ cup flour, ⅓ cup brown sugar, 2 tablespoons granulated sugar, and a pinch of kosher salt. Add the browned butter along with ½ teaspoon vanilla extract and ¼ teaspoon almond extract. Mix with a fork until crumbly clumps form. Place the streusel in the refrigerator while preparing the cake.

In a bowl whisk 6 tablespoons softened butter and ¾ cup powdered sugar until smooth. Add 1 egg, 1 egg yolk, 1½ teaspoons almond extract, and ½ teaspoon vanilla extract and mix until combined. Stir in ¾ cup almond flour, 1 tablespoon all-purpose flour, and ¼ teaspoon salt until a thick paste forms. Set aside.

Preheat oven to 350°F (175°C). Line an 8×8 inch baking pan with parchment paper.

In a large bowl whisk together the cooled brown butter, ½ cup granulated sugar, and ¼ cup brown sugar until smooth. Add 2 eggs, 2 teaspoons vanilla extract, and ¼ teaspoon almond extract and whisk until glossy. Stir in ½ cup yogurt and ¼ cup milk.

In a separate bowl whisk 1½ cups flour, 1 tablespoon milk powder (optional), 1½ teaspoons baking powder, ¼ teaspoon baking soda, and ½ teaspoon kosher salt. Add the dry ingredients to the wet ingredients and mix just until combined.

Spread the batter evenly into the prepared pan. Use a knife or spoon to gently spread the almond filling on top of the cake batter.

Sprinkle the chilled streusel evenly over the top and finish with ½ cup sliced almonds.

Bake for 40–45 minutes, or until a toothpick inserted into the center comes out mostly clean.

Allow the cake to cool in the pan for 15 minutes, then lift it out using the parchment paper.

Dust the top with powdered sugar before slicing and serving.