1. Preheat oven to 350°. Pulse gingersnaps in a food processor 20 times or until finely ground. With processor running, pour butter through food chute, processing until blended. Press mixture into a 9-inch pie plate.
2. Bake at 350° for 15 minutes. Cool on a wire rack 5 minutes.
3. Meanwhile, whisk together sweetened condensed milk and next 3 ingredients. Pour into prepared crust. Bake at 350° for 15 minutes. Chill 2 to 24 hours.
Note: We tested with Smucker's Spiced Apple Butter.