1cup(227g)salted butter, softened to room temperature
¾cup(164g)neutral-flavored oil, like canola, vegetable or grapeseed
1 ¼cups(265g)granulated sugar
¾cup(86g)powdered sugar
½teaspoonbaking soda
½teaspoonbaking powder
½teaspoonsalt
2tablespoonssour cream
2largeeggs
1tablespoonMexican vanilla or pure vanilla extract (see note)
5 ½cups (781g)all-purpose flour
½ to ¾cup(35g)rainbow sprinkles (see note)
Frosting:
¾cup(170g)salted butter, softened to room temperature
2tablespoonssour cream
1teaspoonvanilla extract
6cups(684g)powdered sugar
1 to 2tablespoonsmilk or cream
Instructions
Preheat the oven to 350 degrees F (or 325 degrees F for convection bake) and line several half sheet pans with parchment paper.
In the bowl of a stand mixer fitted with the paddle attachment or in a bowl using a handheld electric mixer, add the butter, oil, granulated sugar and powdered sugar. Sprinkle the baking soda, baking powder, and salt across the top of the sugars and mix until well-combined, 1-2 minutes, scraping down the sides of the bowl as needed.
Add the sour cream, eggs and vanilla and mix for 1-2 minutes, until very well-combined.
Add the flour and mix until a few dry streaks remain. Add the sprinkles and mix by hand until no dry streaks remain and the sprinkles are evenly combined.
Scoop the dough into 2- or 3-tablespoon sized portions (I use a #20 cookie scoop) and roll into balls. Place several inches apart on the prepared baking sheets.
Add 1/2 cup granulated sugar to a shallow dish or bowl. Lightly spray the bottom of a flat-bottomed glass with cooking spray. Dip the bottom of the glass into the sugar and then press each cookie dough ball into a thick circle, about 14 to 1/2-inch thick. Dip the glass into the sugar between each press.
Bake the cookies for 7-8 minutes until just set - the centers may still look slightly under done. It's better to under bake these cookies than to over bake them, so watch closely!
Let the cookies cool for a few minutes on the baking sheets before removing to a cooling rack to cool completely.
For the frosting, in a medium bowl with an electric mixer, whip the butter, sour cream and vanilla until thick and creamy, 1-2 minutes.
Add the powdered sugar and cream (or milk) and mix until well-combined and creamy, 1-2 minutes, scraping down the sides of the bowl as needed. Add food coloring (preferably gel food coloring), if using, and mix until evenly colored and combined. Add additional milk or cream one tablespoon at a time, if needed, to adjust the consistency of the frosting. It should be thick, creamy, and easily spreadable.
Frost the cooled cookies leaving a thin border around the edges.
Notes
Vanilla: because Mexican vanilla is stronger, it helps amplify the cake flavor. If you don't have Mexican vanilla, pure vanilla extract works - make sure to use the full tablespoon. I've talked about this vanilla-butter emulsion for baking, and it is excellent in this recipe for a yummy cake batter flavor. If you have it, add a teaspoon or two in addition to the vanilla extract. Sprinkles: the best sprinkles for this recipe are the jimmie-style rainbow sprinkles. Over Flouring: be careful not to over flour the dough or the cookies might be dry instead of soft after baking. If you don't weigh the flour, make sure to fluff the flour in the container before scooping in the measuring cup and leveling (don't pack or shake the flour into the cup!).