Preheat the oven to 350°F (175°C). Grease and line two 9-inch cake pans with parchment paper.
In a large bowl, whisk together the flour, cocoa powder, sugar, baking powder, baking soda, and salt.
In another bowl, mix the milk, vegetable oil, eggs, and vanilla extract until smooth.
Gradually combine the wet ingredients with the dry ingredients. Stir until just combined.
Carefully add the hot coffee or hot water and mix gently. The batter will be thin.
Divide the batter evenly between the cake pans and bake for 28–32 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cakes to cool completely before assembling.
To make the strawberry filling, place chopped strawberries, sugar, and lemon juice in a saucepan over medium heat. Cook for about 5 minutes until the fruit softens.
Mix the cornstarch and water in a small bowl to form a slurry. Stir it into the strawberry mixture and cook until the filling thickens.
Remove from heat and allow the filling to cool completely.
Place one cake layer on a serving plate. Spread the cooled strawberry filling evenly over the top.
Place the second cake layer on top and chill the assembled cake in the refrigerator for 30 minutes.
Melt the chocolate and coconut oil together in a microwave-safe bowl or using a double boiler. Stir until smooth and glossy.
Remove the chilled cake from the refrigerator and slowly pour the melted chocolate over the top, allowing it to flow down the sides naturally.
Let the chocolate set at room temperature until it forms a crisp shell before slicing and serving.