Preheat oven to 400ºF.
In a large mixing bowl, beat sugar, butter, and vanilla until creamy.
Add egg and beat again.
Add dry ingredients until dough is smooth.
Add green gel food coloring to the dough and beat again until the color is uniform throughout. The amount used will depend on the type of food coloring you are using.
Using a 1-tablespoon cookie scoop, scoop dough and roll it into round balls to form the bodies of the turtles. Place them on a greased cookie sheet.
Using a fork, press the dough balls down in two different directions to create the shell design. Cookies should be about ½-inch thick after being pressed down.
For each turtle, roll a head and four small feet. Gently connect them to the bodies.
Bake cookies for 5-7 minutes or until bottoms begin to brown.
Place cookies onto a cooling rack to cool.
When cookies are cooled, carefully draw eyes on with an edible marker.