Step 1: Line a 12-cup muffin tin with paper or silicone liners. Set aside.
Step 2: In a large mixing bowl, combine the rolled oats, powdered sugar, and salt. Stir well to ensure they are fully mixed.
Step 3: In a separate microwave-safe bowl, combine the peanut butter, melted butter (or coconut oil), and maple syrup (or honey). Microwave for 30-60 seconds, stirring halfway, until the mixture is smooth and warm. Alternatively, heat in a small saucepan over low heat until combined.
Step 4: Pour the warm peanut butter mixture into the bowl with the dry ingredients. Stir vigorously with a sturdy spoon or spatula until the oats are completely coated and a thick, sticky dough forms.
Step 5: Divide the mixture evenly among the 12 prepared muffin cups. Using the back of a spoon or your fingers, press the mixture down firmly into each cup to compact it.
Step 6: (Optional) Drizzle melted chocolate or sprinkle chopped peanuts over the tops of the cups for extra flavor and visual appeal.
Step 7: Refrigerate for at least 1-2 hours, or until the cups are firm and set. Once firm, remove from the muffin tin and store in an airtight container in the refrigerator.