Preheat the oven to 350 degrees Fahrenheit. Line a cookie sheet (or two) with parchment paper or a silicone liner.
In a large mixing bowl, cream together the butter and sugar until light and fluffy.
Add in the half and half, vanilla, and eggs, and beat them into the butter until well combined.
Add in the flour, baking powder, and salt.
Add in some of the neon green food coloring. Mix it all together until you have a nice thick dough. (Add more food coloring as needed for your desired color)
Cover the dough and chill if for 1 hour in the fridge.
Lightly flour a surface and add half of the dough. Roll it out to be about 1/4 inch thick.
Use a Christmas tree cutter to cut out your cookies.
Bend the top of the cookie tree down toward the side to make it like a curl, like the tree in the story.
Place the cookies about an inch apart on the prepared baking sheet.
Bake the cookies for 7 to 9 minutes, until the cookies are just set and the edges start to turn light brown.
Let the cookies cool for 5 minutes on the baking sheet, then transfer them to a cooling rack to cool completely.