If making your own Icing, start here first. For the Icing, mix all ingredients together until you achieve a silky smooth consistency. Add a few drops of food dye to achieve desired color (optional). Set icing aside and start on the cookies.
For The Cookies: In a large bowl, whisk together the flour, baking soda, and salt. When you measure out the flour do not pack it into the measuring cup to avoid using too much flour.
In another large bowl, beat the butter and sugar with a hand mixer for 5 minutes or until light and fluffy then add the egg and mix until thoroughly combined.
Mix in the flour mixture into the wet ingredients with a spatula until just combined.
Roll the sugar cookie dough into about 1 1/2 tablespoon dough balls and place them on your prepared baking sheet lined with parchment paper evenly spaced apart. Bake cookies on the cookie sheet until just golden brown for 10-12 minutes at 350 F.
Let those perfect cookies cool before spreading your icing and sprinkles on top. Spread your icing no more than 1/4-inch thick on top, add your favorite sprinkles and enjoy!
Cover left over cookie dough with plastic wrap and place in the refrigerator until you're ready to bake.