In a large mixing bowl whisk together flour, cornstarch, baking powder baking soda and salt for 20 seconds, set aside. In the bowl of an electric stand mixer fitted with the paddle attachment cream together butter and sugar until blended.
Cover bowl and chill until firm enough to roll, about 2 hours. Preheat oven to 350 degrees during last 10 minutes of chilling.
Line two baking sheets with silicone baking mats or parchment paper. Remove half of the dough from refrigerator.
Shape dough into 9 (1 1/4-inch, 20g) balls, 9 (1-inch, 14g) balls and 9 (3/4-inch, 9g) balls (spray hands with non-stick cooking spray if needed if dough is slightly sticky).
For each snowman, place 3 balls in decreasing sizes with edges just touching on prepared baking sheets spacing them about 3-inches apart. Flatten balls right between 1/2-inch and 1/4-inch.
Bake in preheated oven until nearly set, about 10 - 12 minutes (they should not be doughy). Let cool on baking sheet about 5 minutes then transfer to a wire rack to cool (I like to transfer to an airtight container about halfway through cooling so they don't dry).
Stick one pretzel stick in each side of cookies for arms. Repeat process with remaining dough. Once cool frost with vanilla frosting (I like to add a small amount of frosting to each round then spread outward with an offset spatula).
For the frosting: in the bowl of an electric stand mixer fitted with the paddle attachment cream together butter, powdered sugar, half and half and vanilla until light and fluffy.
Cut or tear a small piece of orange candy then roll and shape into a tiny carrot nose and add to cookies. Decorate with icing as desired. Add mini M&M's for buttons.
Store cookies in an airtight container in a single layer.
Recipe source: adapted from my favorite sugar cookies
*To measure flour (don't fluff flour first) scoop measuring cup into container then level top with a butter knife. If you are in high humidity you made need to add a few extra tablespoons of flour so dough is manageable.
**I transferred mine to piping bags with Wilton #3 tips to get a finer detail for the eyes then used a Wilton #46 tip for the scarves.