Preheat the oven to 350°F/175°C. Line 2 baking sheets with parchment paper.
In a medium bowl, sift together flour, salt, baking powder and baking soda. Set aside.
In a medium bowl, use a mixer fitted with the paddle attachment, beat butter and sugar on medium speed for 1 minute until light and fluffy. Beat in egg and vanilla extract just until combined. Scrape down the sides and up the bottom as needed. Reduce to low speed. Slowly add dry mixture and beat just until combined. Do not overmix.
On a lightly floured surface (or between 2 lightly floured parchment papers), roll the dough to a 1/4-inch thickness. Cut out shapes using a round cookie cutter and place them on prepared baking sheets. Re-roll the remaining scraps into a ball and roll back out to cut the remaining cookies. You also can scoop out the dough using a cookie scoop, then roll into balls and place 2 inches apart onto your cookie sheet. Flatten the top of the balls gently with your palm.
Bake cookies for 10-12 minutes, or until the edges begin to turn brown. Baking time may vary depending on the thickness of the cookies. Remove from the oven and allow cookies to cool on the baking sheets for 10 minutes, then transfer to a wire rack to cool completely.
Make The Frosting: In the bowl of an electric mixer fitted with the paddle attachment, beat all ingredients on medium speed until smooth and creamy and slightly fluffy.
If desired, add 1 drop of red food coloring or any color of your choice and add in more if you want more intense color.
Use an offset spatula to spread the frosting on top of cookies in an even layer. Top with sprinkles and enjoy!