Using a stand mixer, or a handheld mixer and a large mixing bowl, on medium-high speed, cream the unsalted butter for 1 ½ to 2 minutes.
Reduce the mixing speed to low, and add the granulated sugar, cream of tartar. Increase the mixing speed to medium and continue to mix for 2 to 3 minutes or until the butter mixture is fluffy.
Reduce the mixing speed to low and add the egg. Mix until well incorporated.
Add the peppermint extract and clear vanilla flavoring.
Keeping the mixer speed low, slowly add the baking powder and all-purpose flour a ½ cup at a time. Continue mixing just until the flour is well incorporated and no visible streaks of flour are showing.
Divide the cookie dough into 2 equal dough balls. Return 1 dough ball to the mixing bowl to be colored red. Cover the dough ball that is to be the white part of the candy cane cookie and place it in the refrigerator.
Add the ½ teaspoons red gel color to the dough that is left in the mixing bowl. Using the mixer on low speed, add the red coloring into the dough until it has a uniform color and no white streaks are visible. Place the red dough in a medium-size bowl and cover the red dough and refrigerate for 1 hour.
Tip 1: Adding in the peppermint extract is how the cookies will get their peppermint flavor, seemingly magically! Without it, the cookies will taste like normal sugar cookies. So, if you want to have some cookies that are regular, just leave the extract out of that batch. Tip 2: When rolling your dough balls and making the candy canes be sure to cover your counter or a cutting board with a sheet of parchment paper. This will keep from staining the counter or cutting board red. Tip 3: When rolling the ropes and creating the candy cane shapes, it is very important that your hands stay cool. You don’t want to roll them if your hands are too warm or they may lose shape.Tip 4: Be sure to keep the ropes rounded and do not flatten them out when creating the candy cane shapes.