Preheat oven to 350°F (175°C). Grease and line an 8×8-inch pan with parchment paper, leave an overhang for easy removal. Wrap the bottom in foil to prevent water seepage.
Pulse Oreos into fine crumbs and mix with melted butter, pressing evenly into the pan’s bottom. Bake crust for 10 minutes, then reduce oven temperature to 300°F (150°C).
Beat cream cheese until smooth, add sugar and mix well. Incorporate eggs one at a time on low speed, scraping bowl sides between additions. Stir in vanilla, salt, and heavy cream until combined.
Separate about 1 1/4 cups of batter and blend well with cocoa powder and red food gel until evenly colored.
Alternate spooning plain and red batter over the crust. Use a toothpick or skewer to create swirls or shape red dollops into hearts on top.
Place the pan in a larger baking dish with an inch of water (water bath method) and bake for about 75 minutes until the center is slightly jiggly.
Cool cheesecake at room temperature for 20 minutes, then chill in the refrigerator for at least 2 hours before slicing.