- 3 hours
- 15 minutes
- Mix sugar, butter, vanilla and egg in a fridge friendly bowl using an electric mixer or wire whisk. Gradually incorporate flour and baking soda. Wrap in plastic wrap and refrigerate for 2 1 / 2 hours.
- Preheat oven to 375 degrees and spoon 1 tablespoon each cookies onto buttered cookie sheet. Leave room on cookie sheet for cookies to expand as they cook.
- Bake until edges become lightly browned. Wait until cookies are cool before frosting.
- While cookies are cooling, make buttercream. Blend all ingredients in a mini-food processor. Scrape the sides of the processor bowl and blend again. Taste and add more sugar if needed. Turn one cookie upside down and apply buttercream. Top it with a second cookie right side up and sprinkle with sugar crystals if desired. Tip: only frost cookies you plan to serve. Store extra buttercream in fridge and cookies separately.