Preheat your oven to 350°F (175°C).

In a large mixing bowl, cream together 1/2 cup of room temperature unsalted butter and 1/2 cup of granulated sugar until light and fluffy (about 2-3 minutes).

Add in one large egg and 1 teaspoon of pure vanilla extract. Mix until well combined.

In another bowl, whisk together 1 3/4 cups of all-purpose flour, 2 tablespoons of cornstarch, 1/2 teaspoon of baking powder, and 1/4 teaspoon of salt until fully mixed.

Gradually add the dry mixture to the wet mixture; mix until just combined.

Using your hands or a cookie scoop, form the dough into balls about 1 tablespoon in size.

Place them on a parchment-lined baking sheet, leaving about 2 inches between each.

Flatten each ball slightly to create a rounded shape.

Bake in your preheated oven for 10-12 minutes, or until the edges are golden but the centers are still soft.

Let cookies cool on the sheet for a few minutes before transferring to a wire rack to cool completely.

In a medium bowl, whisk together 2 cups of powdered sugar with 2-4 tablespoons of water until glossy and thick but spreadable.

Add gel food coloring for vibrant shades and mix thoroughly.

Spread a generous layer of icing on top of each cookie, letting it drip slightly over the edges.

Place a marshmallow on top as a snowman head.

Use mini chocolate chips for eyes, and pipe or dab on colored gel for details.

Allow the cookies to set at room temperature for about 30 minutes.