Preheat the oven to 350°F (175°C). Grease and flour three 8-inch cake pans.

In a bowl, whisk together cake flour, baking powder, and salt.

In another bowl, beat butter, oil, and sugar until light and fluffy.

Add eggs one at a time, beating well after each addition.

Stir in vanilla extract.

Alternate adding the flour mixture and buttermilk in three parts, starting and ending with the flour.

Divide the batter evenly between pans and bake for 23–28 minutes, until a toothpick comes out clean.

Let cool in pans for 10 minutes, then remove and cool completely on wire racks.

In a large bowl, beat cream cheese and mascarpone until smooth.

Add powdered sugar and vanilla extract; mix until creamy.

In a separate bowl, whip cold heavy cream until stiff peaks form.

Gently fold whipped cream into the cheese mixture until combined.

Level cake layers using a serrated knife.

Optional: Brush cake layers with simple syrup.

Place one cake layer on a serving plate. Spread frosting and top with fresh berries.

Repeat with remaining layers.

Frost the top and sides with remaining Chantilly cream.

Decorate with fresh berries and chill for 30 minutes before serving.