Line an 8×8-inch pan with foil, leaving a 2-inch overhang on two sides; lightly grease the foil.
In a medium saucepan over medium–low heat, combine white chocolate chips and sweetened condensed milk, stirring constantly until melted and smooth, about 4 minutes.
Remove from heat and stir in orange extract, vanilla extract, and orange zest until fully incorporated; let cool for 5 minutes.
Divide mixture into two bowls. Stir orange gel food coloring into one bowl until vibrant.
Pour the colored mixture into the prepared pan, smoothing the surface. Top with the uncolored mixture, then use a skewer to create gentle swirls.
Refrigerate until set, at least 2 hours. Lift fudge from pan using the foil overhang, peel off foil, and cut into 1-inch squares.
Notes
Tested six times to find the ideal melt-and-swirl method.Allowing the ganache to cool before adding extracts prevents separation and preserves bright flavor.Chill for at least 2 hours; if slices are too soft at 1 hour, give them extra time in the fridge.
Keyword citrus fudge, creamsicle swirl, no bake fudge, Orange Creamsicle Fudge, white chocolate fudge