2cupsmarshmallow creamsuch as Marshmallow fluff brand
Instructions
Make the Cookies
Prep. Preheat your oven to 350°F (175°C) with oven racks in upper-middle and lower-middle positions. Then, line four baking sheets with parchment paper.
Combine the wet ingredients. Beat the softened butter, brown sugar, and granulated sugar at medium speed until light and fluffy for about 5 minutes. Then, add the eggs one at a time, followed by the vanilla extract. Continue beating until well combined, scraping down the sides of the bowl as needed.
Combine the dry ingredients. Whisk together the flour, cinnamon, baking soda, baking powder, and salt in a separate large bowl.
Combine both. With the mixer on low speed, add half of the dry ingredients to the butter mixture, then half of the milk. Repeat, ending with the dry ingredients, until all are incorporated. Mix just until combined. Add the quick and old-fashioned oats, stirring by hand or on the lowest mixer setting until evenly distributed.
Shape. Scoop 3–4 tablespoons of dough per cookie onto the prepared baking sheets, spacing them about 2 inches apart. Each baking sheet should fit about six cookies; you’ll have 16–24 cookies.
Bake. Bake the cookies at 350°F for 15–18 minutes, rotating the baking sheets between racks halfway through baking. The cookies should look set and slightly golden at the edges, and a toothpick should come out clean. Transfer to a cooling rack and allow them to cool completely.
Make the Filling
Make the filling. In a clean mixing bowl, beat the softened butter and powdered sugar on medium speed until smooth and fluffy, about 3–4 minutes. Add the vanilla extract and salt, mixing until combined. Add the marshmallow cream and beat until the filling is smooth and fully combined. If the filling seems too soft, refrigerate it for 10–15 minutes to firm it up.
Assemble the whoopie pies. Spread about ¼ cup of the marshmallow filling onto half the cookies’ flat side. Top with the remaining cookies, pressing gently to create a sandwich. Serve immediately, or refrigerate the whoopie pies for a firmer filling.
Notes
If the filling seems too soft and is not staying on the cakes, refrigerate them until it firms up.