Preheat your oven to 350°F (175°C) and grease a 9-inch springform pan. Mix the brownie batter according to package instructions or your preferred homemade recipe, ensuring a smooth consistency. Pour the thick batter into the prepared pan and spread it evenly. Bake for approximately 25-30 minutes, checking for doneness; the edges should be set while the center remains slightly underbaked for that fudgy texture.

While the brownie layer cools, beat 16 ounces of room-temperature cream cheese in a large mixing bowl until creamy and smooth. Gradually add ½ cup of sugar, ½ cup of sour cream, and 1 teaspoon of vanilla extract, blending thoroughly until fully combined.

Once the brownie has cooled to room temperature, gently pour the cream cheese mixture over the brownie layer. Use a spatula to spread it evenly to the edges. Bake the combined layers in the preheated oven for 30-35 minutes until the cheesecake appears mostly set but still has a slight jiggle in the center.

After baking, remove the cheesecake from the oven and let it cool completely at room temperature for about an hour. Once cooled, cover it with plastic wrap and refrigerate for at least 4 hours, ideally overnight.

When ready to serve, take the cheesecake out of the fridge. Drizzle with generous amounts of hot fudge sauce, then add a dollop of whipped cream on top. Finish with a sprinkle of colorful sprinkles and a maraschino cherry.