For the Cookies

• 1 cup unsalted butter, softened
• 3/4 cup firmly packed light brown sugar
• 1/2 cup granulated sugar
• 2 large eggs
• 1 teaspoon pure vanilla extract
• 1 1/2 cups all-purpose flour
• 1 teaspoon baking soda
• 1 teaspoon ground cinnamon
• 1/2 teaspoon salt
• 3 cups old-fashioned oatmeal

For the Cream Filling

• 15 unsalted butter, softened
• 1 1/4 cups confectioners’ sugar, sifted
• 1 1/2 teaspoons pure vanilla extract
• 1 1/2 tablespoons milk or half and half

Make the Cookies

1. Preheat oven to 350°F.
2. In a large bowl create your wet mix:
   • Use a hand mixer to cream together butter and sugars until light and fluffy.
   • Add eggs and vanilla and mix until combined and set aside.
3. In a medium bowl, create your dry mix: whisk flour, baking soda, cinnamon, and salt.
4. Spoon the flour mixture into the wet ingredients in three batches, using a spatula to mix until just combined. Do not over mix.
5. Add in oats and mix until incorporated.
6. Place in the refrigerator to cool
7. Line cookie sheets with parchment paper or a baking mat
8. Scoop out the dough in 2 tbs.-sized dough balls. Shape them and drop onto the cookie sheets.
9. Bake for 12-14 minutes or until golden brown. The
10. Allow cookies to sit on cookie sheets for about 5 minutes before removing them to a wire rack to cool completely. To makes small cookies, use a medium cookie scoop (about 1.5 tablespoons) of dough per cookie and bake for 10-12 minutes. Once cookies have cooled completely, prepare the cream filling.

Now for the Filling

1. In the bowl of a stand mixer fitted with the paddle attachment, beat butter on medium-high speed for about 5 minutes. This process will lighten the color of the butter and ensure you buttercream in extra fluffy.
2. Turn the speed down to low and gradually add in the powdered sugar. Continue mixing on low speed until the powdered sugar is completely incorporated. Add in vanilla extract and milk and mix until combined.
3. Turn mixer back up to medium-high speed and beat the mixture for an additional 3-5 minutes. If needed, add in a little more cream 1 teaspoon at a time until you reach the consistency you desire.
4. To assemble the cookies, pipe or spread the cream filling on the flat side of half of the cookies and put the remaining cookies on top.

Notes

As you can see, I am still mastering the art of flat cookies. According to expert advice, my issue was that I used bread flour instead of all-purpose. Now I know.