1-Creating these frosted sugar cookies is a fun process that results in soft, buttery treats with a light almond flavor. Start by beating the softened butter and sugar until fluffy, which takes about 3-4 minutes. Add the egg and mix well, then on low speed, incorporate the sour cream and vanilla extract for a smooth batter.

2-Next, whisk together the flour, cornstarch, baking soda, baking powder, cream of tartar, and salt in a separate bowl. Gradually mix the dry ingredients into the wet mixture on low speed to avoid overworking the dough. Refrigerate the dough for 1 hour to make it easier to handle, as it can be sticky.

3-Preheat your oven to 375°F (190°C) and line baking sheets with parchment paper. Drop the dough by tablespoonfuls onto the sheets, flattening each with a spoon. Bake for 9 to 13 minutes until the edges turn golden brown, then let the cookies cool completely before frosting.

4-For the frosting, cream the butter until fluffy, then add the salt and vanilla extract. Gradually add the powdered sugar and heavy cream until you reach the desired consistency, and mix in food coloring if you want. Finally, frost the cooled cookies and add candy sprinkles for decoration. The dough might puff up during baking but will flatten as it cools, ensuring a perfect shape.