Preheat the oven to 350°F. Line the bottoms of two 8-inch round cake pans with parchment paper and grease the sides.

Beat the softened salted butter and granulated sugar until pale and fluffy.

Mix in the vanilla extract, then add the eggs one at a time, beating well after each addition.

In a separate bowl, whisk together the flour and baking powder.

Gradually add the dry ingredients to the butter mixture, mixing just until combined.

Stir in the milk.

Divide the batter evenly between the prepared cake pans.

Bake for 20–22 minutes, until a knife or toothpick inserted in the center comes out clean.

Cool the cakes in the pans for 15 minutes, then turn them onto wire racks and cool completely.

Refrigerate the cooled cake layers until firm enough to frost easily.

For the frosting, beat the unsalted butter for 5–8 minutes, until very pale and fluffy.

Add 2 cups powdered sugar, the vanilla extract, vanilla bean seeds, and salt. Beat until smooth.

Add the remaining powdered sugar and heavy cream, then beat until light and fluffy.

Reserve some plain vanilla frosting for decorating if desired.

Gradually beat 1/4 cup raspberry preserves into the remaining frosting until smooth.

Place one cake layer on a serving plate and spread the remaining raspberry preserves over the top.

Spread or pipe a layer of raspberry buttercream over the preserves.

Add the second cake layer, then frost the top and sides with the remaining raspberry buttercream.

Decorate with the reserved vanilla frosting, using rosettes, swirls, or textured ridges as desired.