In a medium saucepan, heat thawed frozen raspberries over medium heat, mashing them gently. Strain to remove seeds, then whisk in sugar and cornstarch, cooking until thickened. Chill.

Preheat your oven to 350°F (175°C) and prepare two 9-inch round cake pans with greasing and parchment.

In a large bowl, whisk together cake flour, baking powder, baking soda, and salt. In another bowl, cream butter and sugar until light and fluffy. Mix in egg whites and vanilla, then alternately add dry mixture and buttermilk.

Pour batter into prepared pans and bake for 35-40 minutes until a toothpick comes out clean. Cool in pans for 30 minutes and then transfer to wire rack.

Combine half & half, sweetened condensed milk, and vanilla in a bowl. Whisk until blended and refrigerate.

Beat butter until fluffy, add cream cheese and mix smooth. Incorporate cooled white chocolate and raspberry jam, then sift in powdered sugar and beat until fluffy.

Level cakes and poke holes in each layer. Soak with vanilla milk, pipe raspberry jam into holes, frost, and assemble the layers.

Slice into 16 pieces, serve chilled or at room temperature.