Place butter and sugar in a large mixing bowl. Beat until creamy.
Add egg whites and vanilla. Beat again until uniform.
Add white cake mix and flour. Beat until dough forms.
Split dough into two bowls. Add blue food coloring to one bowl and green to the other. The amount of food coloring will depend on the potency you are using. Add small amounts until you reach your desired colors of dough.
To create an “Earth” look, grab 5 small pieces of dough, alternating the colors. Gently roll dough into a ball. Don’t work too much. This will can the lines between colors to blur.
Place dough balls on a greased cookie sheet and bake for 10-12 minutes or until bottoms begin to brown.
Remove from oven and quickly press a heart into each cookie. Allow cookies to cool completely.
Notes
Gel food coloring is used in this recipe instead of liquid food coloring to give the cookies more vibrant colors!
Be sure to space the cookies properly on the cookie sheet. You can aim to space them around 2 inches apart. I love these baking mats with the spacers!
Make sure your butter is softened and at room temperature before adding it to the mixture. This will make the mixing process easier and ensure that the butter is completely mixed into the dough.