Creamsicle Cheesecake Bars

Heat oven to 350 degrees F. Line a 9- by 13-inch baking pan with nonstick foil, leaving a 3-inch overhang on two sides. In a food processor, pulse the graham crackers until finely ground. Add the butter and pulse until combined. Press the cookie mixture into the bottom of the prepared pan. Bake until golden brown, 6 to 8 minutes. Meanwhile, clean and dry the food processor. Add the cream cheese, sugar, and flour and process until smooth. Beat in the sour cream, then the eggs and vanilla. Add 1/2 cup orange juice concentrate and beat to combine. Reserve 1/4 cup of the batter and pour the rest on top of the prepared crust. Whisk the remaining 2 tablespoons orange juice concentrate into the reserved batter and transfer to a resealable plastic bag (the mixture will be thin). Snip a tiny bit off one corner of the bag and pipe lines lengthwise over the batter, spacing them 3/4 inch apart (there will be leftover batter). Drag a skewer down through the lines to form a pattern. Bake until the cheesecake is just set (the center should still wobble slightly), 18 to 20 minutes. Let the cheesecake cool completely in the pan, then refrigerate until chilled, at least 3 hours and up to overnight. Using the overhangs, transfer the bar to a cutting board and cut into pieces.