Preheat oven to 350°F (175°C). Grease a 9-inch springform pan and line the bottom with parchment paper.

In a medium bowl, combine the melted butter and sugar. Whisk in the eggs and vanilla extract.

In a separate bowl, whisk together the flour, cocoa powder, and salt. Gently fold the dry ingredients into the wet ingredients until just combined. Do not overmix.

Pour the batter into the prepared pan and spread evenly. Bake for 20-25 minutes, or until a toothpick inserted into the center comes out with moist crumbs. Let cool completely.

In a large bowl, beat the softened cream cheese with an electric mixer on medium speed until completely smooth. Add the sugar and beat until combined.

Mix in the sour cream and vanilla extract. Add the eggs one at a time, mixing on low speed just until combined.

Pour the cheesecake batter over the cooled brownie crust. Wrap the outside of the pan in a double layer of heavy-duty aluminum foil.

Place the springform pan in a large roasting pan. Pour hot water into the roasting pan to come about 1 inch up the sides of the springform pan.

Bake for 60-70 minutes. The edges should be set, but the center will have a slight jiggle. Turn off the oven and let the cheesecake cool in the oven with the door cracked for 1 hour. Remove from the water bath and cool completely on a wire rack.

Refrigerate the cheesecake for at least 6 hours or overnight.

Place the chocolate chips in a heat-resistant bowl. Heat the heavy cream in a saucepan until it just begins to simmer.

Pour the hot cream over the chocolate chips and let it sit for 5 minutes. Whisk until smooth and glossy.

Pour the ganache over the chilled cheesecake. Refrigerate for at least 30 minutes for the ganache to set. Garnish with whipped cream, sprinkles, and a cherry before serving if desired.