Prep: 25 minutes
Total: 1 hour 45 minutes
for the cookies:
560 grams all-purpose flour, plus more for dusting
9 grams baking soda
6 grams kosher salt
300 grams granulated sugar
95 grams shortening
113 grams unsalted butter, softened
2 large eggs
4 grams vanilla extract
250 grams sour cream
for the frosting:
14 grams unsalted butter
75 grams whole milk
450 grams confectioners' sugar
2 grams kosher salt
1. Make the cookies: In a medium bowl, stir the flour, baking soda, and salt together.
2. Meanwhile, paddle the sugar, shortening, and butter in the bowl of a stand mixer on medium-high sped until it's light and fluffy, 2 to 3 minutes. Use a spatula to scrape down the side of the bowl and then add the eggs, one at a time, beating well after each addition. Scrape down the sides of the bowl and add the vanilla, then the flour and sour cream in alternate additions, beginning and ending with the flour. Mix until just combined.
3. Give the cookie dough a little stir with the spatula to make sure no big streaks of unincorporated flour, sugar, or egg exist.
4. Pile the dough on top of a sheet of plastic wrap, cover it, and flatten it into a disc, then refrigerate the dough for at least an hour or up to overnight.
5. This is where it gets tricky: because the dough is super wet, you can't roll it out all at once or you'll have a huge mess on your hands. Divide the dough into 1/8's and work with just that amount at a time. Store the remainder of the dough in the fridge until you're ready to use it.
6. On a lightly floured surface, roll the sough out into 1/4-inch thick or less (they puff a lot while baking). Using a cookie cutter, cut out shapes and place them onto a parchment paper-lined baking sheet. Take the scraps and smush them together and repeat the process one more time. Any remaining dough after that, eat it raw, but feel free to bake it if you prefer.
7. Repeat with the remaining dough. Refrigerate the cookies for 30 minutes before baking.
8. Heat oven to 350°F|175°C. Bake the cookies until they just start to turn brown on the edges, about 15 minutes. Remove from the oven and cool completely before frosting.
9. Make the frosting: Put the milk and melted butter in the bowl of a stand mixer (you could also probably do this by hand with a wooden spoon). Add the powdered sugar and salt and paddle on low until it's combined, then crank it up and paddle another minute just to be sure everything is super smooth. Check the consistency -- it should gooey but not too stiff - it shouldn't hold a peak. You don't want it to be too runny either because it will just run off all over the place. Imagine a consistency somewhere between corn syrup and peanut butter (Not sure if that helps; sometimes you just have to learn by doing).
10. Divide the icing into however many bowls you want, and add food color to each bowl until you have a rainbow of amazing colors to choose from. You can get all professional and use a piping bag with a plain tip to pipe the frosting onto the cookies -- and that's great if you want to go that route. but grandmooh didn't give a fuuuuuuck! She just spooned that shit straight onto the cookies and hers always looked amazing. I don't really understand how. The laws of physics don't seem to make this possible, yet, she managed. So, put the frosting on the cookies however you see fit -- I usually just plop bits of color onto each cookie and then use a spoon to swirl everything around. All of the colors will bleed into each other and it looks cool. Let the icing harden overnight before serving.