Start by lining a large baking tray or cutting board with parchment paper. This will make cleanup super easy!
In a microwave-safe bowl, melt your peanut butter and white chocolate chips on a low or defrost setting. Stir the mixture often until it's smooth and creamy.
Once melted, transfer the mixture into a piping bag and let it cool for about 5 minutes—just enough time for it to be easy to handle but not too thick.
Take your fudge-striped cookies and place them striped side down on the parchment paper.
Snip the tip off your piping bag and pipe a small circle of the melted peanut butter-white chocolate mixture into the center of each cookie.
Place a Reese’s miniature cup upside down (large side down) on top of the piped mixture, pressing gently so that the peanut butter mixture forms a "hat band" around the base of the cup.
For the finishing touch, press a mini M&M onto the hat band to create a cute little buckle.
Now, let your Pilgrim Hats set completely. You can pop them into the fridge for 10-15 minutes to speed up the process.