Get a burst of lemon and sweet buttercream in every bite with these Lemon Sugar Cookie Sandwiches.
Heat oven to 350°F.
In a stand mixer, beat butter and sugar until well combined, about 2 minutes.
If you want to use fresh lemon zest, add it now. (I did not add any with these cookies.)
In a separate bowl, sift together flour, salt, and baking powder. Slowly add the flour mixture (about a cup at a time) to the butter mixture and combine. You can use a mixer or not, it just depends on how strong you are.
Put the dough in plastic wrap and refrigerate for at least one hour.
When you are ready to bake, heat oven to 350°F. Roll dough out, cut out cookies, and bake for 6-8 minutes. Let the cookies cool before assembling the sandwich cookies.
Beat butter in the bowl of a stand mixer with a whisk attachment on medium-high speed until light and fluffy (about 3 minutes).
Add vanilla extract.
With the mixer on low, slowly add in confectioners sugar, milk, and salt, frequently scraping sides and bottom of the bowl.
Once incorporated, whip frosting for at least 3 minutes on medium-high to high (about 7 minutes).
If frosting is too thick, gradually beat in additional milk.
Allow cookies to cool completely before assembly.
Use a small cookie scoop (or a tablespoon) to place the buttercream on the bottom side of one cookie.
Place a second cookie on top of the frosting, pressing down lightly. Enjoy!