Preheat your oven to 350 degrees Fahrenheit and line two large baking sheets with parchment paper. This prevents the cookies from sticking and ensures even browning on the bottom of each treat.
In a large bowl, cream together the softened butter and granulated sugar until the mixture is light and fluffy. Add the egg and the alcohol-free vanilla, beating until well combined. Gradually stir in the flour, baking powder, and salt until a soft dough forms.
Roll the dough into one inch balls and place them two inches apart on the prepared baking sheets. Flatten them slightly with the palm of your hand. Bake for 8 to 10 minutes, or until the edges are just barely golden. Allow the cookies to cool completely on a wire rack before you begin the decorating process.
Spoon a generous dollop of white frosting onto the center of each cooled cookie. Use the back of the spoon to spread the icing toward the edges in an irregular, wavy pattern to mimic the look of a melting puddle of snow.
Place one large marshmallow toward the back edge of the frosted cookie while the icing is still wet. This represents the head of your snowman. Press down gently to make sure it stays in place as the icing sets.
Use the black decorating gel to draw two dots for eyes and a dotted smile on the marshmallow head. Add two black dots on the frosted cookie for buttons and two thin lines for stick arms. Finally, use the orange icing to draw a small triangle for the carrot nose on the marshmallow.
