Line a baking sheet with wax paper; set aside.

Coarsely chop or break the Oreos into pieces. Scatter all of the marshmallows, most of the broken Oreos, and half of the M&Ms evenly over the lined baking sheet.

In a medium microwave-safe bowl, heat the peppermint white chocolate in the microwave for one minute. Remove, stir, then reheat in 30 second intervals until chocolate can be stirred smooth.

Pour melted white chocolate evenly over the dry ingredients on the baking sheet. Use a spatula or the back of a spoon to spread the chocolate over every piece, trying your best to make sure that everything adheres to the chocolate.

Immediately top with the remaining broken Oreos and M&Ms.

In a small microwave-safe bowl, melt the semi-sweet chocolate in the microwave until smooth. Drizzle chocolate evenly over the bark, then top with the sprinkles. Chill bark in the refrigerator until chocolate sets before breaking into pieces and serving.