Oatmeal Cream Pies

Preheat your oven to 350°F (175°C) and grease a cookie sheet.
In a small bowl, stir together the all-purpose flour, baking soda, 1/2 teaspoon salt, and baking powder.
In a large mixing bowl, beat the softened butter and peanut butter with a mixer on medium until combined.
Add the granulated sugar and brown sugar and beat until fluffy.
Beat in the egg and vanilla.
Stir in the flour mixture and rolled oats just until combined.
Drop the cookie dough by teaspoons onto the prepared cookie sheet, spacing them about 2 inches apart.
Bake for 8 to 10 minutes or until the edges are light brown and the centers are set.
Let the cookies cool on the sheet for 1 minute, then transfer them to a wire rack to cool completely.

In a medium bowl, stir together the hot water and 1/4 teaspoon salt until the salt is dissolved.
Add the marshmallow creme, shortening, and powdered sugar.
Beat on medium speed until the filling is smooth and well combined.