Prepare the dish: Line an 8x8 baking dish with parchment paper.
Make the peanut butter mixture: In a large microwave-safe bowl, add peanut butter and maple syrup. Microwave in 20-second intervals, whisking after each time until smooth.
Add oats: Stir in the oats and mix to coat the oats in the peanut butter mixture.
Press into dish: Press the oat mixture into the prepared baking dish and freeze for 10 minutes.
Optional chocolate topping:
In a separate bowl, combine chocolate chips and coconut oil.
Microwave in 30-second intervals, stirring after each time until the mixture is smooth.
Drizzle the melted chocolate over the chilled oat mixture.
Chill: Place the dish in the fridge and chill for 20 more minutes.
Slice and serve: Once chilled, slice into pieces and store in the fridge.