01 - Preheat oven to 325°F (163°C). Grease a 9-inch springform pan and line the base with parchment paper.
02 - Combine graham cracker crumbs, sugar, salt, and melted butter in a bowl. Mix thoroughly and press the mixture evenly into the base of the prepared pan. Bake for 10 minutes, then allow to cool completely.
03 - In a large mixing bowl, beat cream cheese until smooth. Add granulated sugar and vanilla extract, mixing until fully incorporated.
04 - Add eggs one at a time, mixing just until combined after each addition. Fold in sour cream and all-purpose flour until the batter is smooth and free of lumps.
05 - Divide the batter evenly among three bowls. Leave one portion plain, tint one with red gel coloring, and the other with blue gel coloring, adjusting for vibrancy as desired.
06 - Alternate spoonfuls of each colored batter onto the cooled crust to form a patchwork. Swirl gently with a skewer or knife to achieve a marbled appearance, taking care not to overmix.
07 - Bake for 50 to 60 minutes, or until the center is set yet slightly jiggly. Turn off oven, crack the door, and let cool inside for 1 hour.
08 - Refrigerate cheesecake for a minimum of 3 hours before releasing from pan and slicing.