Line small baking sheet (10 inches x 15 inches) with parchment and set aside.
In a heat safe bowl, melt white chocolate in microwave for 90 seconds. Stir and return to microwave for 30 seconds then stir until smooth and completely melted.
Spread a thin layer of melted white chocolate onto parchment with an offset spatula then top with 12 Oreo cookies broken into bits.
Spread remaining white chocolate over Oreo pieces and smooth in an even layer.
Immediately top with reserved Oreos, M&M's, candy corn and sprinkles.
Place pan in refrigerator and chill for 20 minutes. Once set, break bark into uneven shards.
Store in an airtight container at room temperature up to 1 week or in the refrigerator up to 2 weeks.
