If you don't want to use a recipe like the one below, could you just use marshmallow creme?

Here is a link that might be useful: Little Debbie Oatmeal

I made these for a neighbor when we lived overseas and he liked them better than the "Little Debbies";
2c flour
1c granulated sugar
1c brown sugar
1 tsp baking powder
1 tsp baking soda
1/2 tsp salt
1c shortening
2 eggs
1 tsp vanilla
1 1/2c oats
Mix all together. roll in walnut sized balls. Place on ungreased baking sheet and bake at 375° for 10-12 minutes.
Filling
5T Wondra flour
1 c milk
1 c powdered sugar
1/2 c shortening
1/2c butter or marg.
1/4 tsp salt
1 tsp vanilla
Combine flour and milk and cook til thick. Cool and beat in remaining ingredients. Put two cookies together with fillng.
RL`