Directions

1. 1

   Preheat the oven to 350°F. Grease and line the bottoms of three 9-inch round cake pans with parchment paper.

2. 2

   For the chocolate layer, whisk together 1 1/4 cups plus 2 tablespoons flour, 1 1/4 teaspoons baking powder, 3/4 teaspoon baking soda, 1/2 teaspoon salt, and 6 tablespoons cocoa powder in a large mixing bowl.

3. 3

   Add 1/4 cup vegetable oil, 1/2 cup plus 2 tablespoons milk, 1 large egg, and 3/4 teaspoon vanilla extract to the dry ingredients. Stir with a spoon until combined, then beat with an electric mixer on medium speed for 30 to 60 seconds until the batter is smooth.

4. 4

   Slowly pour in 1/2 cup boiling water or very hot coffee while continuing to beat. The batter will be thin. Pour into one prepared cake pan.

5. 5

   While the chocolate batter is prepared, measure out 1 1/4 cups plus 2 tablespoons flour, 1 1/4 teaspoons baking powder, and 1/2 teaspoon salt in separate bowls for each of the two remaining batters and set aside.

6. 6

   In one clean mixing bowl, cream together 1/3 cup softened unsalted butter and 3/4 cup granulated sugar with an electric mixer until light and fluffy, about 2-3 minutes. This will be the vanilla batter.

7. 7

   In another clean mixing bowl, cream together 1/3 cup softened unsalted butter and 3/4 cup granulated sugar with an electric mixer until light and fluffy, about 2-3 minutes. This will be the strawberry batter.

8. 8

   Beat 1 large egg into the vanilla batter until well combined and light, then beat in 1 teaspoon vanilla extract.

9. 9

   Beat 1 large egg into the strawberry batter until well combined and light, then beat in 2 tablespoons dry strawberry Jell-O and 1/4 teaspoon strawberry extract if using.

10. 10

    For the vanilla batter, alternately add the measured flour mixture and milk in three additions, beginning and ending with flour. Stir by hand with a spoon or heavy-duty scraper until the batter is smooth and thick.

11. 11

    For the strawberry batter, alternately add the measured flour mixture and milk in three additions, beginning and ending with flour. Stir by hand with a spoon or heavy-duty scraper until the batter is smooth and thick.

12. 12

    Pour the vanilla batter into the second prepared cake pan and the strawberry batter into the third prepared cake pan.

13. 13

    Place all three cake pans in the preheated 350°F oven and bake for 30 to 35 minutes, until a toothpick inserted in the center of each cake comes out with moist crumbs.

14. 14

    Remove the cakes from the oven and let them cool in their pans for 10 minutes. Then invert each cake onto a wire rack and let cool completely.

15. 15

    While the cakes cool, prepare the frosting. Beat 12 ounces softened unsalted butter in a large mixing bowl with an electric mixer until smooth and creamy.

16. 16

    Gradually add 4 1/2 cups powdered sugar to the butter, beating continuously. After about half the sugar has been incorporated, add 3 tablespoons heavy cream and continue beating in the remaining sugar.

17. 17

    Continue beating and scraping the sides of the bowl, adding whole milk a little at a time as needed, until the frosting reaches a smooth, spreadable consistency. Taste and add more powdered sugar and milk if desired for desired sweetness and texture. Add a pinch of salt and beat to combine.

18. 18

    Place the cooled chocolate cake layer on a serving plate or cake board. Spread a layer of frosting on top.

19. 19

    Place the cooled vanilla cake layer on top of the frosting. Spread another layer of frosting on top.

20. 20

    Place the cooled strawberry cake layer on top. Frost the top and sides of the assembled cake with the remaining buttercream frosting. Serve at room temperature or chill until ready to serve.