Eggless Sugar Cookies

In a small mixing bowl, whisk together flour, baking powder, and salt. In the bowl of a stand mixer fitted with the paddle attachment, beat butter and sugar on medium-high speed until light and fluffy, 4 to 5 minutes. Add sour cream and vanilla and beat to combine. Turn mixer speed to low and gradually add dry ingredients. Mix until just combined. Turn dough out onto a piece of plastic wrap, form into a disc, and refrigerate for at least 1 hour. When ready to bake cookies, set oven rack to the center position and preheat oven to 350 degrees F. Line a baking sheet with parchment paper or a silicone baking mat. On a lightly floured surface, roll dough to 1/4-inch thickness. Use a cookie cutter to cut dough into desired shapes, gathering and re-rolling any leftover dough until it is all used. Place cookie cutouts onto prepared baking sheet. Bake for 10 to 12 minutes, until cookies are just barely golden at the edges. Cool on the baking sheet on a wire rack for 5 minutes, then transfer cookies directly to wire rack to cool completely.