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, mix butter with peanut butter and both sugars until fluffy. Add in the egg and vanilla extract until smooth. Add in the flour mixture and mix until it is fully combined. Fold in the chocolate.
Evenly divide the cookie dough into the muffin liners. Bake for 12-15 minutes.