Combine first 3 ingredients in a small mixing bowl; beat at medium speed with an electric mixer until smooth.
Remove cores from apples using an apple corer.
Using a small spoon, pack peanut butter mixture into core of each apple. Dredge open ends in candy sprinkles, chopped peanuts, or graham cracker crumbs. Wrap apples in plastic wrap, and store in refrigerator up to 2 days.
Serve any remaining peanut butter mixture as a spread for apple slices or graham crackers.
