Mix your dough: Add your cake mix, eggs, oil, and vanilla extract to a large mixing bowl. Mix on medium speed until combined. Add your green food coloring one drop at a time until you reach your desired color and mix on low until just combined (I used 5 drops of gel food coloring). Cover dough and let it chill in fridge for 30 minutes so it’s easier to scoop.
Roll your cookies: Whisk together powdered sugar and cornstarch in a bowl. Using a cookie scoop or a spoon, scoop a 1-2 tablespoon size ball of dough and plop it into your powdered sugar and cornstarch mixture. Dough will be really sticky but once it lands in the powdered sugar it’s easier to handle. Roll it around until covered and place on a baking sheet lined with parchment paper or a silicone baking mat.
Bake your cookies: Bake cookies at 375° for 8-10 minutes or until the center is just set but the cookies haven’t started to brown on top yet.
Add heart and cool: While still warm, add your heart sprinkle and after 3-5 minutes transfer to a cooling rack to completely cool.
Notes
Tips for Making Grinch Cookies:
Try adding flavored extracts like mint, pistachio, or almond to your dough for a fun twist!
Make sure to mix the dough fully once you add your green food coloring so you don’t have any white streaks in your dough.
If you don’t have cornstarch you can just roll the cookies in powdered sugar—some will sink into the cookie but you should still get a dusted effect.
Make sure to keep an eye on your cookies so they don’t start to brown as that will affect the pretty green color of the cookie. These cookies should be soft and chewy.
If you don’t have heart sprinkles on hand, you could also use pink royal icing to pipe on the shape of a heart once the cookies are cool.
Storage and Freezing:In an airtight container, Grinch cookies will last for about 5 days before starting to get stale.To freeze, put your cookie sheet in the freezer to first flash freeze the cookies for 30 minutes and then you can put them in a freezer bag for 2-3 months. Let the cookies thaw in the fridge or on the counter before eating.