Preheat your oven to 350°F and line two cookie sheets with parchment paper. In a shallow bowl, combine the powdered sugar and cornstarch—this mixture will coat your cookies and give them that signature crackled, shiny Grinch look. Set this coating mixture aside within easy reach, as you'll use it right after scooping the dough.

In a mixing bowl, combine the softened butter, canola oil, and room-temperature eggs. Beat them together for about 30 seconds until the mixture is light and well combined. Using room-temperature eggs is important here—they blend more smoothly into the fat, creating a better emulsion and more cohesive dough. The oil adds tenderness to these cake-mix cookies, which is a nice contrast to their crispy-crackled exterior.

Add the entire cake mix to the wet mixture and stir until just combined—don't overmix, as this will overwork the gluten and make the cookies tough. Once the dry ingredients are incorporated, add 3-5 drops of green food coloring (start with 3 drops and add more if you want a deeper, more sinister Grinch green). Fold the coloring in gently until the dough is evenly tinted throughout. I prefer gel food coloring here because it gives a more vibrant green without adding extra liquid that can throw off the dough's consistency.

Using a cookie scoop or spoon, scoop rounded portions of the green dough and drop them directly into the powdered sugar and cornstarch mixture from Step 1. Roll each scoop gently to coat all sides evenly—this coating creates the crackled, textured surface that makes these cookies visually appealing and gives them a delicate crispy exterior. Place each coated cookie about 2 inches apart on the prepared cookie sheets, as they will spread slightly during baking.

Bake the cookies in your preheated 350°F oven for 8-10 minutes. The cookies should look slightly underdone on top—they'll have a soft center with those beautiful crackled edges. The exact time depends on your oven and the size of your scoops, so start checking at 8 minutes. Don't overbake these, or they'll lose their tender cake-like texture and the powdered sugar coating will begin to brown rather than stay white and contrasted.

Remove the cookies from the oven and let them rest on the baking sheet for 5 minutes—this allows them to set up enough to handle without breaking apart. Transfer them to a wire cooling rack to cool completely. If you're using heart-shaped sprinkles for the Grinch theme, press them gently onto the warm cookies right after removing them from the oven so they'll stick. The contrast between the soft, cake-like interior and the crackled, powdered sugar coating becomes even more pronounced as they cool.