Using a stand mixer with a paddle attachment, or hand mixer, cream the room temperature butter, brown sugar, and granulated sugar until smooth and creamy.
Add in the egg, vanilla extract, and peppermint extract and beat until light, fluffy, and pale in color. This should take 2-4 minutes which seems like a long time, but you'll see a huge difference in the texture afterwards.
Add in the flour, baking soda, and salt and mix until thoroughly combined. The dough will be soft.
If desired, scoop about ⅓ of the dough into a separate bowl and mix in some red and green jimmies.
Then using a 2 tablespoon cookie scoop to portion the dough, roll into small balls. For the other two types of dough, dip the tops in red/green sparkling sugar and non-pareils [or whatever other sprinkles you want].
Cover the dough balls and chill in the fridge for 2 hours.
While the dough is chilling, preheat the oven to 350°F and line a baking sheet with parchment paper.
Place dough balls at least 2-3 inches apart on the baking sheet (they will spread, I usually only do 6 cookies on a half sheet pan). Place the rest of the cookie dough balls back in the fridge while the first batch cooks.
Bake at 350°F for 8-10 minutes or until the edges are fully set but the centers are still soft.
Remove the Christmas sugar cookies from the oven and let rest on the baking sheet for 2-3 minutes, then transfer to a cooling rack.
Notes
Store cookies in an airtight container at room temperature for up to 4 days (they'll definitely be gone before then though).Freeze pre-rolled cookie dough balls in the freezer for up to 6 months.