Preparation Time: 20 minutes
1. PREP: Line 1 extra large or 2 sheet pans with parchment paper or Silpat liners. Set aside. In a very large bowl or on a platter, add the popped popcorn, miniature marshmallows, and 1 and 1/2 cups of Valentine's Day M&M's. Toss and set aside.
2. WHITE CHOCOLATE: Place the white chocolate chips and shortening or oil in a microwave-safe bowl. Microwave in bursts of 25 seconds stirring in between each burst until the chocolate is melted and smooth. Be patient to avoid burning the chocolate. Once white chocolate is smooth and fully melted, pour over the popcorn. Working quickly, toss the ingredients together to coat all the ingredients in the white chocolate.
3. MILK CHOCOLATE: Immediately pour the white chocolate coated popcorn on to the prepared sheet pan(s). Spread into 1 even layer. Melt the chocolate with 1/2 teaspoon of the remaining shortening or oil. Microwave in 15 second bursts, stirring between each burst. Transfer melted chocolate to a small zipper-top plastic bag and cut a tiny tip off corner with scissors (or use a pastry bag fitted with a #3 tip). Drizzle the chocolate evenly and generously over all the popcorn. While the chocolate is still soft, press remaining 1/2 cup Valentine's M&M's into the popcorn.
4. HARDEN: Let popcorn harden at room temperature (or in the fridge) until solid. Break into pieces and enjoy! Store any leftovers in an airtight container at room temperature. Best if used within 1-2 days.