Coarsely chop Oreo cookies and place in the center of a large baking sheet.
Chop white chocolate into large chunks, and place in a microwave safe bowl. Heat for 1 minute and stir. Continue with 15-20 second intervals until the chocolate is completely melted and smooth.
Pour chocolate over the Oreo cookies, and carefully spread into an even thin layer.
Sprinkle M&M's evenly over the top and decorate with sprinkles.
Let the chocolate completely set up (on the counter or in the fridge) before slicing into pieces to serve.