Line a 13 X9 pan with heavy foil. Grease with butter. Set aside. Have your ingredients set out and ready to put into the candy. You will need to work fast.
Melt butter in large pot - stir in evaporated milk, sugar, and vanilla extract. Bring to a rolling boil. Boil until candy reaches the soft-ball stage. Remove from heat. SPRINKLE into hot candy one bag of white chocolate chips. Stir until chips are melted. Reserve 1 cup of this mixture. Pour rest into prepared pan. Quickly, add 1 teaspoon of orange extract and approximately 2 drops of orange food coloring into the reserved mixture. Then swirl thru the fudge in the prepared pan. Set aside to cool. Cool completely before trying to cut. Store fudge in tightly covered container.