Preparation Steps

• Preheat oven to 350°F. Line baking sheets with parchment paper.
• In a stand mixer fitted with the paddle attachment, cream together butter, granulated sugar, and confectioners' sugar until just combined.
• Drizzle in vegetable oil and add eggs; mix well until fully incorporated.
• Whisk together flour, cream of tartar, and kosher salt in a separate bowl.
• Slowly add the dry flour mixture to the wet ingredients and mix until the dough pulls away from the sides of the bowl.
• Using a 2-tablespoon scoop, drop dough balls onto the prepared baking sheets.
• Roll each dough ball smooth and round, then press each with the bottom of a wet glass dipped in granulated sugar, flattening the center slightly.
• Bake for 7 to 9 minutes until edges just start to brown and centers no longer appear wet. Remove and let cool.
• For the frosting, mix butter, sour cream, and salt in a clean bowl until fully combined.
• Gradually add confectioners' sugar about 0.5 cups at a time until the frosting reaches desired thickness.
• Add a few drops of red food coloring and mix until frosting turns a soft pink.
• Spread the pink frosting onto cooled cookies using an offset spatula or butter knife.