Preheat the oven to 350°F (175°C). Grease and flour a 9x13 inch baking dish.

In a mixing bowl, whisk together flour, sugar, cocoa powder, baking powder, and salt.

In another bowl, mix milk, vegetable oil, eggs, and vanilla extract until well combined.

Combine the wet and dry ingredients, mixing until just combined.

Pour the batter into the prepared baking dish and bake for 30 minutes or until a toothpick comes out clean.

In a bowl, whisk together sweetened condensed milk, evaporated milk, and whole milk.

Once the cake is baked, let it cool for 10 minutes, then poke holes all over the top with a fork.

Pour the milk mixture over the cake, allowing it to soak in. Let it cool completely.

In a mixing bowl, whip the heavy cream with powdered sugar and vanilla extract until soft peaks form.

Spread the whipped cream over the cooled cake.

Chill in the refrigerator for at least 2 hours before serving.