Preheat the oven to 350° and lightly grease a baking sheet(s).

In a medium bowl, whisk flour, baking powder and salt together. Set aside.

In a large bowl, beat butter, oil and sour cream together on medium speed using an electric mixer, or a stand mixer, for one minute.

Add sugar and vanilla extract and beat until smooth.

Add dry ingredients into wet ingredients and mix on low speed just until dough forms a ball.

Roll the dough into about ¾ inch size dough balls and place on the prepared baking sheets.

Spray the bottom of a glass with non-stick cooking spray and gently press each cookie to flattened them a bit.

Bake for 8 minutes.

Remove cookies from the oven and let cool for 5 minutes and then remove and place on a wire rack to cool completely.

In a medium mixing bowl, cream butter, milk and vanilla together. Gradually add powdered sugar and beat until smooth and creamy.

Frost cookies once they have completely cooled, and sprinkle with candy sprinkles.