In a medium bowl, mix together the melted butter, nut butter, honey or maple syrup, vanilla, cinnamon, nutmeg (if using), and salt until smooth.
Stir in the oats until fully coated and the mixture comes together.
Fold in chocolate chips or raisins, if using.
Chill the mixture in the refrigerator for 20–30 minutes to make rolling easier.
Roll into 12–14 bite-sized balls.
Store in the refrigerator or freezer until ready to enjoy.