First, in a small bowl, whisk together the cornstarch and water until smooth. Set it aside.
Grab a medium pan and combine the chopped strawberries, sugar, and lemon juice. Cook over medium-low heat, stirring occasionally, until it starts to gently simmer. Reduce the heat to low and let it cook for about 8-10 minutes, or until the mixture has noticeably reduced and thickened slightly.
Stir in the cornstarch mixture. Continue cooking for a couple more minutes until it's nice and thick β it should cling to the back of a spoon.
Remove the pan from the heat and let the filling cool down completely. Once cooled, pop it into an airtight container and chill it in the fridge for at least an hour. This helps it set perfectly!
Preheat your oven to 350Β°F (175Β°C). Lightly grease two 8-inch round cake pans and line the bottoms with parchment paper β this is a pro tip for easy cake removal!
In a large bowl, whisk together the flour, cocoa powder, sugar, salt, baking powder, and baking soda.
Now, add in the eggs, vanilla extract, oil, and milk. Pour in the hot water and mix everything until the batter is smooth. Be careful not to overmix!
Divide the delicious batter evenly between your prepared cake pans. Bake for 20-26 minutes, or until a toothpick inserted into the center comes out clean.
Let the cakes cool in their pans for about 20 minutes before carefully transferring them to a wire rack to cool completely. Patience is key here for perfect layers!
While the cakes are cooling, let's make that luscious buttercream! In a large bowl, beat the softened butter until creamy.
Gradually add the powdered sugar, mixing slowly at first, then increasing speed until combined and fluffy.
Stir in ΒΌ cup of your chilled strawberry cake filling. Mix until it's perfectly smooth and combined. If you want it a bit thicker, add a touch more powdered sugar.
Keep the buttercream in the fridge until your cake layers are completely cool.
Once everything is completely cool, it's assembly time! Place one cake layer onto your serving plate. Pipe a thick border of strawberry buttercream around the edge of this layer.
Spoon the remaining strawberry filling into the center, spreading it gently within the frosting border.
Carefully place the second cake layer on top. Now, frost the top and sides of the cake with the rest of your dreamy strawberry buttercream. Decorate as you wish and get ready to enjoy this delightful creation!