Preheat your oven to 350°F (175°C).
Grease a 9x13 inch baking pan with butter or line it with parchment paper for easy removal later.
In a large bowl, melt 1 cup of butter and mix in 2 cups of sugar until smooth. Add 4 large eggs, one at a time, mixing well after each addition. Stir in 1 teaspoon of vanilla extract.
In another bowl, whisk together 1 cup of flour, 1 cup of cocoa powder, and a pinch of salt. Gradually add this mixture to the wet ingredients, stirring until just combined.
Pour half of the brownie batter into the prepared pan, spreading it evenly. Save the other half for later!
In a mixing bowl, beat 8 oz of cream cheese until smooth. Add 1/2 cup of sugar, 1 egg, and 1 teaspoon of vanilla extract. Mix until creamy and well combined.
Spread the cheesecake mixture over the brownie layer in the pan. Be gentle to keep the layers distinct!
Carefully dollop the remaining brownie batter over the cheesecake layer. Use a knife to swirl it slightly for a marbled effect.
Chop up 3-4 Milky Way bars and sprinkle them on top of the batter for that extra indulgence.
Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted comes out with a few moist crumbs.
Let the brownies cool in the pan for at least 20 minutes before cutting into squares. Enjoy your epic indulgence!