Line a 9 x 9 inch baking pan with parchment paper.
In a microwave-safe bowl, heat the milk chocolate for 1 minute. Stir, then heat an additional 20-30 seconds until completely melted. Spread from edge to edge in the baking pan with a spatula.
In another microwave-safe bowl, heat the white chocolate for 1 minute. Stir, then heat an additional 20-30 seconds until completely melted. Whisk in the food coloring. You can add a drop or two more if you prefer a deeper pink hue.
Spread the white chocolate on top of the milk chocolate. Use a skewer or toothpick to swirl the chocolates together. Sprinkle the M&Ms and heart candies overtop.
Chill the bark in the fridge for 1 hour. Use a sharp knife to chop large chunks of bark for serving.