I preheat my oven to 350°F (175°C) and grease two 8-inch round cake pans. I also line the bottoms with parchment paper to prevent sticking.

In a bowl, I whisk together flour, baking powder, and salt. This ensures even distribution of the leavening agent.

I beat the butter, oil, and sugar together in a large mixing bowl until light and fluffy. This step gives the cake a tender crumb.

I add egg whites one at a time, mixing well after each addition. Then I stir in the vanilla extract for flavor.

I add the flour mixture and milk alternately, starting and ending with the flour. I mix until just combined, being careful not to overmix.

I pour the batter evenly into the pans and bake for 25–30 minutes, or until a toothpick comes out clean. After baking, I let the cakes cool in the pans for 10 minutes before transferring them to a wire rack.

In a bowl, I beat the butter until creamy. I gradually add cocoa powder and powdered sugar, alternating with heavy cream, until smooth. Then I mix in vanilla and a pinch of salt. If the frosting feels too thick, I add a little more cream.

Once the cakes cool completely, I spread frosting between the layers, then frost the top and sides. I smooth it with an offset spatula or leave swirls for a rustic look.