Nestle's publishes a recipe for milk chocolate popcorn on VeryBestBaking.com. Another good recipe is Taste Of Home's striped chocolate popcorn, which uses a chocolate drizzle.
To make milk chocolate popcorn, combine 12 cups of popped corn and 1 can of salted peanuts in a greased roasting pan. In a heavy-duty saucepan, combine 1 3/4 cups of milk chocolate morsels, 1 cup of light corn syrup and 1/4 cup of butter. Cook it over medium heat, stir until the mixture starts to boil, and pour it over the popcorn. Toss well so all the popcorn is coated, and bake it for 30 to 40 minutes in an oven preheated to 300 degrees Fahrenheit. Let the popcorn cool in the pan, and transfer it to a serving plate lined with wax paper.
For the striped chocolate popcorn, combine 12 cups of popped corn, 2 cups of miniature pretzels and 1 cup of toasted and halved pecans in a bowl. Drizzle it with 1/4 cup of melted butter, toss it, and set it aside. In a microwave, melt 4 ounces of chopped white candy coating for one minute, and stir. Microwave it for additional 10- to 20-second intervals, and stir until smooth. Drizzle the mixture over the popcorn, toss it, and spread it on baking sheets lined with foil. Melt 2 ounces of chopped milk chocolate candy coating in a microwave, and drizzle it over the popcorn. Let it stand until the chocolate sets.