Oatmeal Whoopie Pies

Original recipe found here

2 cups brown sugar
1/2 cup butter, softened
1/4 cup shortening
2 eggs
1/2 tsp salt
1 tsp cinnamon
1 tsp baking powder
3 TBSP boiling water
1 tsp baking soda
2-1/2 cups flour
2 cups quick oats

-Preheat oven to 350º.

-Cream brown sugar, butter, and shortening. Add eggs and mix. Add salt, cinnamon, and baking powder and mix. Mix baking soda and boiling water, then add to the bowl and mix. Add flour and oatmeal and mix well. 

-Scoop dough onto parchment-lined cookie sheets so that you have rounded heaping teaspoons. Bake for 10 minutes, being careful not to burn. Remove from oven, transfer to a cooling rack, and let the cookies cool completely.

Filling recipe found here

• 5 Tablespoons Flour
• 1 cup Milk
• 1 teaspoon Vanilla
• 1 cup Butter
• 1 cup Granulated Sugar (not Powdered Sugar!)
• -In a small saucepan, whisk flour into milk and heat, stirring constantly, until it thickens (you want it to be very thick, thicker than cake mix, more like a brownie mix is).
  -Remove from heat and let it cool to room temperature (it must be completely cool before you use it in the next step).
  -Stir in vanilla.         
  -While the mixture is cooling, cream the butter and sugar together until light and fluffy, then add the completely cooled milk mixture and beat THOROUGHLY (if it looks separated, you haven’t beaten it enough!). Beat it until it all combines and resembles whipped cream.
• -Using a small size cookie scoop, put a scoop of filling on one oatmeal cookie, then top with a second oatmeal cookie. Lightly press together.