Peanut Butter S’mores Sandwich Cookies

Ingredients:

For the Peanut Butter Cookies:

1 cup (2 sticks) unsalted butter, softened

¾ cup creamy peanut butter

¾ cup granulated sugar

¾ cup packed brown sugar

1 large egg

1 teaspoon vanilla extract

2 cups all-purpose flour

½ teaspoon baking soda

¼ teaspoon salt

For the Marshmallow Filling