In a small saucepan, melt butter. Stir in sugar and corn syrup. Cook over medium until mixture comes to a boil, then continue to boil for 5 minutes, stirring occasionally.
Remove from heat and stir in the vanilla and food coloring. Pour over popcorn and toss to coat, Pour onto a baking pan sprayed with cooking spray.
Bake at 250ยบ for 45 minutes, mixing around every 15 minutes. Spread on wax paper.