Preheat the oven to 350°F and line cookie sheets with parchment paper.
Mix dry ingredients (2 min): In a large bowl, whisk the dry ingredients together until combine.
3 1/4 cups all-purpose flour, 2 Tablespoons cornstarch, 1/2 teaspoon salt
Beat wet ingredients (5 min): In the bowl of a stand mixer with the paddle attachment, or large bowl with electric mixer, beat the butter and sugar on high for 2 minutes. Turn the mixer on low and add the avocado oil, egg, vanilla, and almond extract until combined, stopping to scrape down the sides and bottom of the bowl as needed.
1 cup unsalted butter, 1 cup granulated sugar, 1/2 cup vegetable oil, 1 large egg, 2 teaspoons vanilla extract, 1 teaspoon almond extract
Combine and add sprinkles (3 min): (With the mixer on low, add the dry ingredients until combined. Stir in the sprinkles with a rubber spatula.
1/2 cup holiday jimmies
Scoop and bake (10 min): Use a large cookie scoop to drop the dough onto the prepared baking sheet 2-3 inches apart. Bake in the preheated oven for 10-12 minutes, until the edges are set and the tops look just set. Cool on the cookie sheet for 5 minutes and swirl with a glass or large cookie cutter for a perfect circle if desired. Transfer to a cooling rack to cool completely.
Make the frosting an decorate (10 min): In a large bowl with a hand mixer or stand mixer fitted with the paddle attachment, beat the butter on medium speed until smooth. Add the powdered sugar and vanilla and beat for 2-3 minutes, until light and fluffy. Add more powdered sugar a Tablespoon at a time to thicken it to desired consistency. Stir in the sprinkles and spread the frosting on the cooled cookies.
3/4 cup unsalted butter, 2 1/2 cups powdered sugar, 1 1/2 teaspoons vanilla extract, Kosher salt to tast, 1/4 cup holiday jimmies