Preheat your oven to 350°F (175°C). Grease and flour a 9x13-inch baking pan.
In a large mixing bowl, combine the strawberry cake mix, vegetable oil, eggs, and water. Mix on medium speed until smooth and well blended, about 2-3 minutes.
Gently fold in the chopped fresh strawberries until evenly distributed in the batter.
Pour half of the batter into the prepared baking pan and set aside the remaining batter.
In another bowl, beat the softened cream cheese until smooth. Gradually add the powdered sugar, vanilla extract, and cocoa powder, mixing until well combined.
Spoon dollops of the cream cheese mixture over the first layer of cake batter. Use a toothpick or knife to swirl it slightly into the batter.
Pour the remaining strawberry batter over the cream cheese layer, making sure to cover it completely.
Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted in the center comes out clean.
Once baked, let the cake cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely.
While the cake is cooling, whisk together the milk and whipped cream until fluffy.
Once the cake has cooled, spread the whipped cream topping evenly over the top.