01 - Preheat oven to 325°F. Grease a 9-inch springform pan and line the base with parchment paper.
02 - Combine graham cracker crumbs, granulated sugar, salt, and melted butter in a bowl. Mix thoroughly. Press mixture evenly into the bottom of the pan. Bake for 10 minutes, then allow to cool completely.
03 - In a large mixing bowl, beat softened cream cheese until smooth. Add sugar and vanilla extract, mixing until fully incorporated.
04 - Add eggs one at a time, blending gently after each addition to avoid excess air. Mix in sour cream and flour until batter is creamy and smooth.
05 - Divide batter evenly among three bowls. Leave one portion uncolored. Tint the second portion with red gel food coloring, and the third with blue gel food coloring, mixing gently until desired intensity is achieved.
06 - Alternate spoonfuls of plain, red, and blue batters over the cooled crust, forming a patchwork pattern. Use a skewer or knife to create gentle swirls for a marbled effect, taking care not to overmix.
07 - Bake for 50 to 60 minutes, or until center is just set yet slightly jiggly when shaken. Turn off oven, crack the door, and allow cheesecake to rest inside for 1 hour.
08 - Remove pan from oven. Place cheesecake in the refrigerator and chill for at least 3 hours prior to slicing and serving.