Make the Chocolate Cake:

• Preheat the oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
• In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
• Add the eggs, milk, vegetable oil, and vanilla extract. Mix until combined and smooth.
• Gradually add the boiling water to the batter, mixing until smooth (the batter will be thin).
• Pour the batter evenly into the prepared cake pans and bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
• Let the cakes cool in the pans for 10 minutes, then remove from the pans and transfer to a wire rack to cool completely.

Make the Strawberry Filling:

• In a medium saucepan, combine the chopped strawberries, sugar, and lemon juice. Cook over medium heat for about 5-7 minutes, stirring occasionally until the strawberries release their juice and begin to soften.
• In a small bowl, mix the cornstarch with cold water to create a slurry. Add this to the strawberry mixture and continue cooking, stirring constantly, until the filling thickens (about 2-3 minutes).
• Remove from heat and let the strawberry filling cool completely.

Prepare the Frosting:

• In a large mixing bowl, beat the softened butter until creamy.
• Gradually add the powdered sugar, cocoa powder, vanilla extract, and 3 tablespoons of heavy cream. Beat until smooth and fluffy.
• Adjust the consistency by adding more heavy cream, one tablespoon at a time, if necessary.

Assemble the Cake:

• Place one layer of the chocolate cake on a serving platter or cake stand.
• Spread an even layer of the cooled strawberry filling over the first cake layer.
• Place the second layer of cake on top and press gently to secure.
• Frost the entire cake with the chocolate frosting, smoothing it out with a spatula.
• Optionally, garnish with fresh strawberries or chocolate shavings.

Serve and Enjoy:

• Slice and serve the cake. Enjoy the combination of rich chocolate and fresh strawberry filling!