01 - Preheat oven to 325°F. Grease a 9-inch springform pan and line base with parchment paper.
02 - Blend graham cracker crumbs, sugar, salt, and melted butter in a bowl. Firmly press mixture into bottom of pan. Bake for 10 minutes, then cool completely.
03 - Beat cream cheese in a large mixing bowl until thoroughly smooth. Add sugar and vanilla extract; mix until fully incorporated.
04 - Add eggs one at a time, beating briefly after each until just blended. Gently fold in sour cream and flour until smooth.
05 - Separate batter evenly into three bowls. Leave one plain, tint one with red gel food coloring, and tint the third with blue gel food coloring until the desired hue is reached.
06 - Alternately spoon plain, red, and blue batters over cooled crust in patches. Use a skewer or knife to gently swirl for a marbled appearance without blending the colors completely.
07 - Transfer to oven and bake for 50 to 60 minutes until set at the edges and just slightly jiggly at the center. Turn off oven, crack door, and leave cheesecake inside to cool for 1 hour.
08 - Refrigerate baked cheesecake for at least 3 hours prior to slicing for optimal texture and flavor.