For the cookies:

Cup of Yum
1. Line 2 sheet pans with parchment paper. Set aside.
2. Place soft butter in a medium-size mixing bowl. Stir with a wooden spoon or sturdy spatula until nice and smooth. Add powdered sugar and vanilla. Mix together by hand for about 30 seconds, until fluffy and well blended.
3. Sprinkle the flour and cornstarch evenly over the top. Stir until flour is incorporated and the dough is shaggy. Turn out onto a lightly floured surface and press dough in a ball. Knead a few times until fairly smooth then form into a ball again and press with your hands into a flat disk.
4. On a lightly floured work surface, roll out dough to a ⅜-inch thickness. Keep work surface, dough and rolling pin lightly dusted with flour. Cut circles and place on prepared pans. Re-roll scraps as many times as needed to use up the dough.
5. Place cutouts in the refrigerator for at least one hour or up to 24 hours.
6. When ready to bake, preheat oven to 350˚F. Remove cookies from refrigerator and bake for 12-16 minutes or until just beginning to turn golden at the edges. Rotate pans halfway through for even browning. Cool completely before icing.

For the glaze:

1. Combine powdered sugar, half and half and ¼ teaspoon peppermint (or other flavored) extract in a medium-size bowl. Mix until smooth. The glaze should be thick but pourable. Add a little more half and half if too thick. Taste the glaze and add more peppermint extract, if needed (see the note above in the post).
2. Dip the tip of a small knife into the blue food coloring and swirl some of it into the icing. Stir well and add more food color until desired shade of blue is achieved. Transfer the glaze to a shallow bowl.

To glaze the cookies:

1. Holding onto the edges of a cookie, dip the top surface into the glaze, being sure all of the surfaces touch the glaze. Pull cookie up and out of the glaze. Allow excess glaze to drip back into a separate bowl.
2. When the glaze stops dripping, quickly flip the cookie right side up and give it a gentle jiggle to allow the glaze to flow evenly over the surface. Repeat with remaining cookies. Allow glaze to dry for 15-30 minutes.

For the buttercream piping:

1. Place butter in a medium-size bowl and stir until smooth. Add powdered sugar, 1½ tablespoons of half and half and the mint extract and stir vigorously until smooth, adding a bit more half and half, if needed to achieve a fairly thick but spoonable consistency.
2. Place buttercream in a pastry bag fitted with a small round icing tip (I used a Wilton #3 round tip). Starting at the upper edge of one cookie, pipe the Christmas trees by making increasingly wider lines, stopping about ¼-inch above the lower edge of the cookie (see pictures in the post). Immediately sprinkle trees with a few more white nonpareils. Set aside to dry.