435 g (3 1/2 cups) flour
1 1/2 teaspoons baking soda
1/4 teaspoon salt
230 g (1 cup) unsalted butter, at room temperature
150 g (3/4 cup) granulated sugar
115 g (1/2 cup) sour cream
1 teaspoon vanilla
115 g (1/2 cup) unsalted butter, at room temperature
320 g (2 cups) powdered sugar
2 tablespoons milk
1. Preheat the oven to 300ËF (150ËC).
2. In a large bowl, whisk the flour, baking soda, and salt to combine.
3. In a separate large bowl, cream the butter and sugar together using a hand mixer until light and fluffy, about 5 minutes.
4. Add the egg and mix until fully incorporated.
5. Add the sour cream and vanilla and mix until creamy.
6. Add the flour mixture, a third at a time, until fully combined.
7. Shape the dough into a rectangle and wrap in plastic wrap.
8. Chill the dough for 1 hour in the refrigerator.
9. Make the frosting: in a large bowl, beat the butter with a hand mixer until fluffy. Sift in powdered sugar and mix until incorporated. Add milk and continue to beat until the frosting is smooth and velvety.
10. Remove the plastic wrap from the dough and lightly flour clean surface.
11. Roll out the dough to about Â½-inch (1 1/4 cm) thick. Cut out circles using a glass or cookie cutter.
12. Transfer the cookies to a parchment paper-lined baking sheet, leaving about 1 inch (2 1/2 cm) between the cookies.
13. Bake for 8 minutes, until the bottoms are golden brown and the tops of the cookies are pale.
14. Let cookies cool on the pan or a wire rack.
15. Frost the cookies and decorate as you wish.