In a medium bowl, combine flour, baking soda, and salt; set aside. In the bowl of a stand mixer fitted with a paddle attachment, cream together butter, oil, sugar, and confectioners sugar until light, about 3 minutes. The batter will be on the soft, wet side.
Add egg and vanilla and beat to combine. Add dry ingredients and mix just until dough comes together. Dough will be very soft but wrap it in plastic wrap and refrigerate for at least one hour.
Preheat oven to 350°F. Line two baking sheets with parchment paper.
Fill a shallow bowl with sprinkles of choice. Use a 1-ounce cookie scoop (or a rounded tablespoon) to form cookies into balls. Roll each ball in sprinkles to cover and place on parchment lined baking sheet.
Bake until cookies are golden at the edges, about 12 minutes. Let cool 5 minutes then transfer to a wire rack to finish cooling. Cookies will keep in an airtight container for up to 3 days.