Prepare the Brownie Base

1. Preheat oven to 325°F (165°C).
2. Line a springform pan with parchment paper.
3. In a bowl, whisk the flour, cocoa powder, sugar, salt, and baking powder.
4. Add the oil, egg, milk, and vanilla. Mix until smooth.
5. Spread evenly into the bottom of the springform pan.
6. Bake for 15–18 minutes. Cool slightly.

Prepare the Cheesecake Filling

1. Beat the cream cheese and sugar until smooth.
2. Add the eggs one at a time, mixing on low speed.
3. Add sour cream and vanilla extract. Mix just until combined.
4. Pour over the cooled brownie layer.

Bake the Cheesecake

1. Wrap the springform pan in foil and place in a water bath.
2. Bake at 325°F (165°C) for 60–70 minutes, or until the center is set.
3. Turn off the oven and let the cheesecake cool inside for 1 hour.
4. Remove, cool completely, then refrigerate at least 6 hours or overnight.

Add Toppings

1. Warm the hot fudge sauce and pour it over the chilled cheesecake.
2. Top with whipped cream and cherries before serving.
3. Add nuts or chocolate chips if desired.