In a mixing bowl, stir together the peanut butter, pure maple syrup and vanilla extract until well-combined. Note: if your peanut butter has been sitting in the refrigerator and is cold, microwave it for 20 second intervals until it softens up and is very easy to stir. If need be, you can heat all the ingredients together in a small saucepan on the stove top, but you should be able to mix everything together in a mixing bowl.

Stir in the oats and sea salt until combined and a thick dough forms.

Lightly spray 8 to 10 holes of a muffin tin with cooking spray. This helps release the peanut butter cups from the muffin tray once they have set up. Note: if you have a mini muffin tin and want smaller chocolate peanut butter oat cups, feel free to make mini muffin sizes.

Divide the peanut butter mixture between 8 to 10 muffin holes, creating the size of peanut butter cups you want (I make 8 large peanut butter cups).

Transfer the chocolate chips and coconut oil (or butter or peanut butter) to a microwave safe bowl and microwave for 20-second increments, stirring well in between intervals, until the chocolate chips have completely melted.

Spoon the melted chocolate mixture over the peanut butter layer. If desired, sprinkle the tops of each peanut butter cup (on top of the chocolate layer) with flakey sea salt.

Freeze the peanut butter cups in the freezer for 1-2 hours, or until they have completely set up.

Use a butter knife to run along the edge of the peanut butter cups to lift them out of the muffin tin. Enjoy!