Snickerdoodle Sandwich Cookies with Marshmallow Buttercream Filling

Hello to the most amazing creation ever made!! No seriously this is NO joke.  When it comes to cookies I'm a die-hard chocolate chip cookie lover, homemade of course, and fresh out of the oven.  I like other cookies too, but I'm picky.  So, when I tried a cookie similar to this at a local restaurant I was seriously blown away.  I had never tried anything like it.  The flavor combination is out of this world!  And totally genius, if you ask me. The cinnamon-y and slightly salty cookie with the sweetness of the marshmallow buttercream.  OH. MY.

So, without further ado, I give you the Snickerdoodle Sandwich cookie with Marshmallow Buttercream Filling.

Snickerdoodle Sandwich Cookies with Marshmallow Buttercream Filling
for the cookies: 
1 cup unsalted butter, room temperature
3/4 cup granulated sugar
1/2 cup brown sugar
1 large egg, plus 1 yolk
1 Tbsp. vanilla extract
1 tsp. baking soda
1 tsp. cream of tartar
1/2 tsp. salt
1 tsp. cinnamon
2 3/4 cups all-purpose flour

for the cinnamon sugar mixture:
2 Tbsp. granulated sugar
1 1/2 tsp. cinnamon

 For the frosting:
1/2 cup unsalted butter, room temperature 
1 Tbsp. vanilla extract
1 7-oz jar marshmallow fluff
3 cups powdered sugar
1-2 tsp. milk, if necessary


Preheat oven to 325 degrees F.

In the bowl of a stand mixer, beat butter and sugars until light and fluffy, about 2-3 minutes.  Add in egg, yolk and  vanilla and beat for another minute, scraping down the sides as necessary.

In a separate bowl, sift together baking soda, cream of tartar, salt, cinnamon and flour.  Gradually add it to the butter and sugar and beat until well incorporated.

Mix the cinnamon sugar in a small bowl.  Using a small cookie scoop or a spoon, scoop out dough  and roll into a ball, about 1-inch.  Roll the tops of each dough ball in the cinnamon sugar mixture then place them on a cookie sheet, about 9 to a pan.  Do not over crowd.

Bake about 10-12 minutes, turning cookie sheet halfway through baking. Try not to underbake them, as you will need them to be sturdy while spreading the frosting.  Cool cookies completely on a wire rack.  You can even place them in the fridge so they are more firm.

To make frosting, place butter in the bowl of a stand mixer.  Whip until creamy. Add in marshmallow fluff and beat 2-3 minutes, then add in vanilla.  Add in the powdered sugar, 1 cup at a time, until fully incorporated. Beat another 2-3 minutes.  If frosting is too thin, add a little more sugar, if it's too thick add a little milk, 1 teaspoon at a time. (You will most likely have extra frosting.  Nothing that another batch of cookies later won't remedy...or there's always a spoon or a graham cracker.)

To make sandwich cookies, frost the bottom of one cookie then top with another.  Continue until you've used all the cookies.  Store in an airtight container either on the counter or in the fridge (I actually like mine chilled so I keep them in the fridge.)