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. Press mixture firmly into the pan base. Bake for 10 minutes, then remove to cool.
03 - Using an electric mixer, beat softened cream cheese until smooth. Add granulated sugar and vanilla extract; blend until fully incorporated.
04 - Add eggs one at a time, beating briefly after each addition. Fold in sour cream and flour until batter is homogenous.
05 - Divide the batter evenly among three bowls. Leave one portion uncolored. Tint the remaining bowls with red and blue gel food colorings to reach the desired intensity.
06 - Spoon alternating colors of batter over the cooled crust to form a patchwork pattern. Gently swirl with a skewer or knife for a marbled effect, avoiding overmixing.
07 - Bake for 50 to 60 minutes, or until the center is just set but remains slightly jiggly. Turn oven off, crack door, and allow cheesecake to cool inside for 1 hour.
08 - Transfer cheesecake to refrigerator and chill for at least 3 hours before slicing and serving.