swig sugar cookie bars

the goods:

1/2 cup unsalted butter, room temperature
1/4 cup plus 2 tablespoons vegetable oil
1/2 cup plus 2 tablespoons granulated sugar
1/4 cup plus 2 tablespoons confectioners' sugar
1 egg
1 tablespoon water
1 teaspoon vanilla extract
2 and 3/4 cup all-purpose flour
1/2 teaspoon salt
1/2 teaspoon baking powder
pinch of baking soda
1 tablespoon additional sugar for sprinkling

frosting:
1/4 cup unsalted butter, room temperature
3 tablespoons sour cream
1 and 1/2 cups confectioners' sugar
pinch of salt
dash of vanilla extract
2 tablespoons heavy whipping cream

Preheat oven to 350 degrees. Lightly grease a 9x13-inch pan and set aside. Using a stand mixer, thoroughly cream butter, oil, granulated sugar, and confectioners' sugar until well combined. Scrape down sides of bowl and add egg, water, and vanilla; mix until combined. Add flour, salt, baking powder, and baking soda; mix until completely combined.
Spread/press cookie mixture evenly into the prepared pan (helpful trick: put your hand inside a sandwich bag and lightly spray it with cooking spray). Evenly sprinkle sugar over bars before baking for 14-15 minutes. Let cool completely.
In a stand mixer, combine butter, sour cream, confectioners' sugar, salt, and vanilla until well combined. Add in the cream until frosting is smooth. Frost bars and refrigerate until ready to cut and serve. Bars are best cold.