Preheat your oven to 350°F (175°C). Grease and flour a 9x13-inch baking dish.
In a large mixing bowl, combine the flour, sugar, cocoa powder, baking powder, and salt. Whisk until well blended.
Add the milk, vegetable oil, eggs, and vanilla extract to the dry ingredients. Mix on medium speed for 2 minutes until smooth.
Stir in the boiling water until fully combined (the batter will be thin). Pour the batter into the prepared baking dish.
Bake for 30-35 minutes or until a toothpick inserted in the center comes out clean. Allow the cake to cool in the pan for 10 minutes, then poke holes all over the top using a fork or skewer.
In a small saucepan over low heat, melt the white chocolate chips until smooth. Pour the melted chocolate over the cake, ensuring it seeps into the holes. Let the cake cool completely.
In a medium bowl, whip the heavy cream with powdered sugar and vanilla extract until stiff peaks form. Gently fold in the fresh raspberries.
Spread the raspberry whipped cream over the cooled cake. Drizzle with raspberry sauce before serving.
Chill the cake in the refrigerator for at least 1 hour before slicing.