Prepping the oven: Preheat your oven to 350°F (175°C). Grease and flour two 9-inch cake pans.
Mixing dry ingredients: In a bowl, whisk together flour, baking powder, and salt.
Creaming butter and sugar: In another bowl, cream the unsalted butter and sugar together until light and fluffy.
Combining: Add eggs one at a time, mixing well after each addition. Stir in vanilla extract.
Alternating dry ingredients and milk: Gradually add the dry ingredients to the creamed mixture, alternating with the milk. Start and end with dry ingredients. Gently fold in the fresh raspberries.
Baking the cake: Divide the batter between the prepared pans and bake for about 25-30 minutes or until a toothpick inserted into the center comes out clean.
Making the raspberry filling: In a saucepan over medium heat, combine raspberries, sugar, and water. Cook until the berries break down, and then add the cornstarch mixture. Cook until thickened, then remove from heat and let cool.
Preparing the white chocolate glaze: Beat softened butter until creamy, then gradually add sifted powdered sugar. Melt white chocolate with heavy cream and vanilla, and mix it until smooth.
Assembling the cake: Once the cakes are cooled, layer one cake, spread raspberry filling on top, add the second layer, and frost with white chocolate glaze. Decorate with fresh raspberries.