Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners.
In a medium bowl, combine the brownie mix, vegetable oil, egg, and water. Stir until well blended.
Divide the brownie batter evenly among the muffin cups, filling each about halfway.
In another bowl, beat the softened cream cheese until smooth. Add the granulated sugar, vanilla extract, and one egg, mixing until fully combined.
Fold in the mini chocolate chips into the cream cheese mixture.
Spoon the cream cheese mixture over the brownie batter in each muffin cup, filling them almost to the top.
Bake in the preheated oven for 20-25 minutes, or until the cheesecake is set and the brownie is cooked through.
Remove from the oven and let cool in the pan for 10 minutes before transferring to a wire rack to cool completely.
Once cooled, top each cheesecake cup with whipped cream, a drizzle of chocolate syrup, and chopped nuts if desired.