1. Preheat the oven to 350°F (177°C). Grease and flour three 8-inch round cake pans.

2. In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

3. In a large bowl, cream the butter and sugar until light and fluffy, about 3-4 minutes.

4. Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

5. Gradually add the dry ingredients to the butter mixture, alternating with the buttermilk, beginning and ending with the dry ingredients. Mix until just combined.

6. Divide the batter evenly between three bowls. Leave one plain for the vanilla layer. Add cocoa powder to the second bowl and mix until combined for the chocolate layer. Add strawberry puree to the third bowl and mix until combined for the strawberry layer.

7. Pour each batter into a prepared cake pan and smooth the tops with a spatula.

8. Bake for 22-25 minutes, or until a toothpick inserted in the centers comes out clean.

9. Allow the cakes to cool in the pans for 10 minutes before turning out onto a wire rack to cool completely.

10. While the cakes cool, prepare the buttercream frosting. In a large bowl, cream the butter until smooth. Gradually add the powdered sugar, mixing on low speed until combined. Add the heavy cream and vanilla extract, then mix on medium-high speed until light and fluffy, about 2-3 minutes.

11. Once the cakes have cooled, level them with a serrated knife if needed.

12. Place the chocolate cake layer on a cake board or serving plate. Spread a thin layer of buttercream on top. Add the strawberry cake layer and spread another thin layer of buttercream. Top with the vanilla cake layer.

13. Apply a thin crumb coat of buttercream over the entire cake. Chill in the refrigerator for 20-30 minutes.

14. Frost the cake with a final, smooth layer of buttercream. Chill again for at least 30 minutes.

15. Prepare the white chocolate ganache drip. In a microwave-safe bowl, heat the heavy cream until steaming. Pour over the chopped white chocolate and let sit for 1 minute. Stir until smooth.

16. Pour the ganache over the chilled cake, allowing it to drip down the sides. Chill for 10 minutes to set.

17. Fill a piping bag fitted with a petal tip with remaining buttercream. Pipe roses around the top edge of the cake.

18. Serve chilled and enjoy!