In a small bowl, beat an egg with a whisk. Add in 1 teaspoon vanilla extract, ¼ teaspoon peppermint extract , ¾ teaspoon salt and ⅛ teaspoon green gel food coloring. Set aside.
In another bowl, mix together 2½ cups of flour, ¼ teaspoon baking soda and ¼ teaspoon baking powder. Set aside.
Cut up 2 sticks (1 cup) of cold (straight from the refrigerator) butter into ½ inch chunks.
Process the butter and 1 cup of granulated sugar in the food processor until combined, about 30 seconds.
Add the egg mixture to the food processor and blend until combined, another 30 seconds.
Add the flour mixture and process until all of the flour is combined, about 30 seconds.
Divide the dough into two parts.
Roll the first one into a ball.
Put the ball of dough in between 2 large sheets of parchment paper.
Use the rolling pin to roll the dough out to about 1/8" thick.
Put the rolled out dough on a cookie sheet or tray, still keeping the parchment paper on both sides.
Repeat with the other ball of dough.
Refrigerate the rolled out dough for 1½ hours, or freeze for 30 minutes.
When the cookie dough is stiff, take the first sheet out of the refrigerator (leaving the other one in).
Peel off the top layer of parchment paper.
Cut hearts in the cookie dough with the cookie cutter.
Use a thin spatula (or a cake knife) to separate the cookies from the bottom layer of parchment paper. If the dough has become soft and is losing its shape, put it back in the refrigerator for 15 to 20 minutes until it is stiff again. This will make the cookies easier to remove.
Repeat the process with the other sheet of cookie dough.
Cover a cookie sheet with a piece of parchment paper.
Then lay out the cookies about ½ inch apart.
Bake at 300℉ for 12 to 16 minutes, until the cookies have an even color across the top but are not brown.
Remove from the oven and push a large sprinkle heart into the middle of each cookie.
Let cool for 5 minutes on the cookie sheet. Then move to a wire rack and let them cool completely.
Roll out the left over dough to create another batch of cookies.
Using parchment paper on both sides of the cookie dough while rolling will keep the dough from sticking to the rolling pin.
Refrigerating the cookie dough prevents the cookies from losing their shape while they are baking
Parchment paper on the cookie sheet keeps the cookies from spreading and maintains the heart shape.
Only bake one cookie sheet at a time since stacking them in the oven will cause uneven heating.
The cookies can be stored in an airtight container at room temperature for about 3 days, in the refrigerator for about a week or in the freezer for up to 3 months.