For the Oatmeal Cookies:
Makes 16 sandwiches
1 1/2 cups all-purpose flour
1 teaspoon baking soda
1 teaspoon salt
1/2 teaspoon cinnamon
1 cup (2 sticks) butter, softened
1 1/2 cup brown sugar
1 egg
1 1/2 teaspoons vanilla
2 cups old-fashioned oats
Preheat oven to 350 degrees. 
In a medium bowl, whisk the flour, baking soda, salt and cinnamon to blend. Set aside.
In
 the bowl of an electric mixer set on medium speed, cream the butter and
 sugar together for 3 minutes, or until light and fluffy. Add the egg 
and vanilla and continue beating until well combined, scraping down the 
sides as necessary. 
With the mixer on low speed, gradually add the flour mixture, mixing until just combined. Mix in the oats at low speed.
Drop
 the batter in rounded tablespoons, 2 inches apart, onto baking sheets. 
Bake 10 minutes or until light brown 
For the filling:
2 TBSP milk
Powdered sugar (keep adding till it makes it thick)
1 tsp cinnamon
Melt butter and add milk, mix well then add sugar till thick. stir in cinn until mixed completely
ENJOY!!

