Cream butter in the bowl of stand mixer on medium speed. Add granulated sugar, beat until light and fluffy, then add powdered sugar and beat until incorporated.
Add eggs, one at a time, scraping down bowl after each addition. Add vanilla extract, followed by coconut milk. Allow mixture to come together, scrape down bowl again if needed.
Add baking soda, cream of tartar, and flour and mix until just incorporated.
Chill dough (optional but recommended in order to roll into dough balls with hands) for 15-20 minutes.
Preheat oven to 350 degrees and line a sheet tray with parchment paper.
Roll dough balls of approximately 2 Tablespoons each and arrange on sheet tray. Top with sprinkles.
Bake for 12-15 minutes or until cookies are cooked through.
Recipe by WITHBUTTERANDLOVE at https://www.withbutterandlove.com/secret-ingredient-softbatch-sugar-cookies/