Step 1: In a medium bowl, combine the all-purpose flour, 1/2 cup granulated sugar, baking powder, and 1/2 tsp salt. Whisk until well combined.
Step 2: In a separate large bowl, whisk together the softened unsalted butter, eggs, 1 cup milk, 1 tsp vanilla extract, and melted white chocolate chips until smooth.
Step 3: Gradually add the wet ingredients to the dry ingredients, mixing with a spatula or spoon until just combined. Be careful not to overmix the batter.
Step 4: Pour the batter into a greased and floured 9-inch cake pan. Bake in a preheated oven at 350°F (175°C) for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Let the cake cool in the pan for 10 minutes, then invert onto a wire rack to cool completely.
Step 5: While the cake cools, prepare the raspberry filling. In a small saucepan, combine the 2 cups fresh raspberries, 1/4 cup granulated sugar, and 1 tbsp lemon juice. Cook over medium heat, stirring occasionally, until the raspberries break down and the mixture thickens, about 8-10 minutes.
Step 6: Remove the raspberry filling from heat and let it cool completely to room temperature. It will thicken further as it cools.
Step 7: To prepare the frosting, in a chilled bowl, whip the 1 cup heavy cream, 1/2 cup powdered sugar, and 1 tsp vanilla extract using an electric mixer on high speed until stiff peaks form.
Step 8: Once the cake is completely cool, spread the cooled raspberry filling evenly over the top of the cake. Then, gently spread the whipped cream frosting over the raspberry filling.
Step 9: Garnish the cake with fresh raspberries and white chocolate shavings, if desired. Serve immediately and enjoy your White Chocolate Raspberry Dream Cake!