• Whisk the flour, salt, and baking powder in a medium bowl and set aside.
• In a large bowl, use an electric mixer to beat the softened butter until smooth and creamy. Add the granulated sugar and beat until light and fluffy.
• Add the egg yolks and mix until well combined.
• Mix in about half of the dry ingredients, then add the sour cream, followed by the rest of the dry ingredients. Mix until the dough comes together.
• Chill the cookie dough for at least 1 hour before rolling and cutting into shapes.
• Preheat your oven to 350°F. Line 2 large baking sheets with parchment paper or silicone baking mats.
• Roll and cut the dough: Lightly sprinkle a clean surface with flour. Lightly sprinkle both sides of the dough and a rolling pin with flour and roll the dough out to ¼-inch thick.
• Dip your cookie cutters in sugar or flour and cut out as many shapes as you can from the dough.
• Gather up the dough, re-roll and cut out more shapes until all of the dough is used. To keep the dough from sticking, try sprinkling it with granulated sugar instead of flour. That way you aren't adding too much extra flour to the dough, which can make the cookies dry.
• Bake: Arrange the cookie shapes on your lined baking sheet and bake in the preheated oven for 12 minutes, or until light golden brown around the edges. Remove from the oven and let cool completely on the baking sheet.

Cream Cheese Icing:

• Use an electric mixer to beat the softened butter and cream cheese until smooth with no lumps.
• In 2-3 additions, add the powdered sugar and mix on low speed until incorporated after each. Mix in the vanilla extract and salt.
• Divide the icing between bowls and add a few drops of gel coloring to each, if desired.
• Decorate: Use a piping bag and small piping tip to decorate the cookies with the cream cheese icing. Once decorated, lay the cookies flat in a single layer so the icing can set.