Preheat your oven to 350° F and line your baking sheets with parchment paper.
In a large bowl, add your softened butter, sugar and brown sugar and cream together until smooth. Add your egg, egg yolk and vanilla and mix until combined. Mixture should be fluffy in texture.
Next, add your flour, cornstarch, baking soda, and salt. Fold until well combined.
Add your green and yellow food coloring and mix until combined and until you've reached your desired color.
Scoop your cookie dough into 1-2 inch balls and roll in sugar. Place on baking sheets lined with parchment paper a few inches apart.
Bake for 8-10 minutes. Cookies will spread but I like to use a round cookie cutter or large mason jar lid to scoot the cookies and keep them round. (You could also use the back of a spoon the scoot the cookies)
Let cool.
For Frosting:
In a large bowl of a stand or hand mixer, add your softened butter and whip for about three minutes until butter becomes pale in color.
Add your powdered sugar about a cup at a time. When mixture gets stiff add your heavy cream and vanilla extract, whip it up and then add your remaining powdered sugar. If your frosting is too runny, add more powdered sugar and if it's too stiff, add more heavy whipping cream, a little bit at a time.
Once your frosting is done, add your red food coloring and mix. Transfer you red frosting into a piping bag fitted with a small round tip.
To Assemble:
With your red icing, pipe a heart in the middle of your cookies. Make sure your cookies have cooled before piping frosting. Apply pressure and move down inward letting go of pressure as you go down. Do this on each side forming a heart.
Once all your cookies are piped with hearts, you're ready to serve, share and enjoy!!
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