Step 1: Preparing the Strawberry Puree

• Place 2 cups (280g) of chopped strawberries in a blender and puree until smooth.
• Transfer the puree to a saucepan and cook over medium heat, stirring constantly, until it reduces by half to 1/2 cup plus 2 tablespoons, about 15 minutes.
• Allow the puree to cool to room temperature. This will be used for both the cake batter and the strawberry frosting.

Step 2: Preparing the Cake Pans

• Preheat the oven to 350°F (176°C).
• Grease three 8-inch round cake pans and line the bottoms with parchment paper circles. Grease the sides of the pans as well to prevent sticking.

Step 3: Making the Cake Batter

• In a large mixing bowl, beat together 10 tablespoons (140g) of unsalted butter, 1/2 cup plus 2 tablespoons (150ml) of vegetable oil, and 2 cups (414g) of sugar until light and fluffy.
• Add 5 large eggs, one at a time, beating well after each addition.
• In a separate bowl, whisk together 2 3/4 cups (358g) of flour, 3 teaspoons of baking powder, and 3/4 teaspoon of salt.
• Gradually add the dry ingredients to the wet mixture, alternating with 1 cup plus 2 tablespoons (270ml) of milk, starting and ending with the dry ingredients.
• Divide the batter into three portions.

Strawberry Cake Layer:

• Take 2 1/4 cups of batter and mix with 1 tablespoon of milk, 1/2 cup plus 2 tablespoons of strawberry puree, 1 teaspoon of strawberry extract, and 10 drops of red food coloring. Fold in 2 tablespoons of flour.
• Pour into one of the prepared pans.

Vanilla Cake Layer:

• Add 1/2 teaspoon of vanilla extract to another 2 1/4 cups of batter. Fold in 2 tablespoons of flour.
• Pour into the second prepared pan.

Chocolate Cake Layer:

• Melt 2.5 oz bittersweet chocolate and fold into the remaining batter along with 2 tablespoons of cocoa powder.
• Pour into the third prepared pan.

Step 4: Baking the Cake Layers

• Bake the cake layers for 23-28 minutes, checking for doneness with a toothpick.
• Allow the cakes to cool in the pans for 2-3 minutes before turning them out onto wire racks to cool completely.

Making the Frostings

Chocolate Buttercream:

1. Cream the Butter: Beat 1 cup (224g) unsalted butter until smooth and creamy.
2. Incorporate Cocoa Powder: Gradually add 1/2 cup (57g) cocoa powder, mixing on low speed.
3. Adjust Consistency: Add 4-5 tablespoons (60-75ml) heavy cream or water until the frosting reaches a spreadable consistency. Mix in 1 teaspoon vanilla extract and 1/4 teaspoon salt.

Vanilla Buttercream:

1. Prepare the Base: Beat 2 1/2 cups (560g) unsalted butter until creamy.
2. Incorporate Sugar: Gradually add 10 cups (1150g) powdered sugar, alternating with 4-6 tablespoons (60-90ml) cream or water. Mix in 2 1/2 teaspoons vanilla extract and a pinch of salt until smooth and spreadable.

Strawberry Buttercream:

1. Prepare the Base: Take 2 cups of vanilla buttercream and mix in 1/4 cup of strawberry puree and 3/4 teaspoon of strawberry extract.

Assembling the Cake

1. Level the Cake Layers: Use a serrated knife to remove any domes from the cake layers.
2. Stack the Layers: Place the chocolate layer on a serving plate, spread with chocolate buttercream, add the strawberry layer, spread with strawberry buttercream, and finally add the vanilla layer, spread with vanilla buttercream.
3. Apply the Final Frosting: Apply a crumb coat, then frost the cake with the remaining buttercreams, creating distinct layers on the sides.

Adding the Chocolate Ganache Drip

1. Make the Ganache: Heat 1/4 cup (60ml) of heavy cream until simmering. Pour over 3 oz (85g) of semi-sweet chocolate chips and let sit for 3-5 minutes. Whisk until smooth.
2. Drizzle the Ganache: Use a squeeze bottle or spoon to drizzle the ganache around the edge of the cake, allowing it to drip down the sides.

Final Decorating Tips

1. Piping Buttercream Swirls: Use a piping bag to pipe swirls of vanilla buttercream on top of the cake.
2. Garnishing with Strawberries: Add fresh strawberries on top just before serving to avoid sogginess.