Prepare Your Baking Sheet: Line a baking sheet with parchment paper or a silicone baking mat to prevent the chocolate from sticking.
Melt the Chocolate:
Melt the milk chocolate in a heatproof bowl over a pot of simmering water (double boiler method) or in the microwave in 30-second intervals, stirring between each interval until smooth.
Create the Chocolate Base:
Pour the melted milk chocolate onto the prepared baking sheet, spreading it out evenly with a spatula to about 1/4 inch thick.
Decorate with Reindeer Faces:
Place the 12 mini pretzels onto the chocolate for the reindeer antlers.
Add 12 red M&M's below the pretzels for the reindeer noses.
Place candy eyes above the noses to complete the reindeer faces.
Add Green M&M's and Sprinkles:
Scatter the green M&M's and 1 teaspoon of sprinkles over the bark while the chocolate is still wet for added festive color and texture.
Set the Chocolate:
Let the bark sit at room temperature until fully set, or place it in the refrigerator for about 20-30 minutes to speed up the process.
Break and Serve:
Once the chocolate is completely set, break it into pieces with your hands. Enjoy your festive reindeer bark or package it up as a holiday treat for friends and family!