The Mocha Sandwich Cookies that Dad Dreams About

I continue to be surprised (although I shouldn't) at the times Andy mentions something I baked years ago. This time his reverie involved a sandwich cookie I'd allegedly made with a coffee buttercream filling. He first dropped the hint about these cookies a few months ago, at which time I deployed evasive maneuvers. Now, however, he's invoking the power of his birthday and it's time to make good. These cookies didn't ring a bell for me (again- no surprise) but Andy remembered enough to tell me to check our old Mrs. Fields cookie cookbook. I found the cookie he remembered, and must have turned it into a sandwich cookie. Now I'm documenting it here so when he asks for these again in a few years, I'll be ready. They freeze well, so they also serve to restock the treasure chest.

For the buttercream, I thought this recipe sounded good. The half-batch was barely enough- next time try a 3/4 batch.

Coffee Buttercream

1 tsp instant coffee or espresso powder
2 1/2 tsp whole milk, room temperature (I used half Kahlua)
1/2 Cup (1 stick) butter, room temperature
1 3/4 Cups powdered sugar
1 tsp pure vanilla extract
1/8 tsp salt, or to taste

Combine the instant coffee with the milk and set aside. In the bowl of a stand mixer, cream the butter on med-high until light and fluffy (about 5 minutes), scraping down the bowl and paddle a few times in between.

Add the powdered sugar a bit at a time, scraping down the bowl and paddle between intervals. Then add the vanilla, the coffee/espresso milk mixture, and salt. Mix on low until fully incorporated, about one minute.