Preheat the oven to 350 F. Line a 12 cup muffin pan with paper liners. In a medium bowl, whisk together flour, salt, and baking soda. In a large bowl, combine butter with both granulated and brown sugars until fluffy.
Add in the egg and vanilla extract, and mix until smooth. Add in the flour mixture, mix until it is fully combined. Fold in the chocolate chips and Reese's pieces. Evenly divide the cookie dough between the prepared paper liners. Bake for 12-15 minutes.