Preheat your oven to 350°F (177°C) and prepare three 7-inch round cake pans by greasing them and lining the bottoms with parchment paper.

In a medium bowl, whisk together the cake flour, baking powder, and salt until well combined.

In a large mixing bowl, combine the granulated sugar, unsalted butter, and vegetable oil, and beat until pale and fluffy, about 3–4 minutes. Gradually add the large egg whites, mixing well after each addition.

Mix in the sour cream, vanilla extract, and almond extract until fully combined.

Gradually add the dry flour mixture, alternating with the milk, starting and ending with the flour.

Divide the batter evenly among the prepared cake pans and bake for 26–30 minutes, or until a toothpick inserted into the center comes out clean. Let cool in pans for 15 minutes.

While the cakes cool, make the Swiss meringue buttercream by whipping together egg whites and granulated sugar over simmering water. Transfer to a stand mixer and beat until stiff peaks form.

Gradually add the soft, room-temperature butter to the whipped egg whites, mixing until smooth and creamy.

In a saucepan, combine frozen raspberries, granulated sugar, and lemon juice over medium heat, simmer, then stir in cornstarch slurry to thicken. Strain to remove seeds and cool.

Level the cooled cake layers with a serrated knife, then assemble with buttercream and raspberry filling between layers.

Chill the assembled cake for about 20 minutes, then frost with remaining buttercream.

Decorate with fresh raspberries and slivered almonds before serving.