To make the cookies: Heat oven to 350°F. Line two baking sheets with parchment paper. Set aside.
In a mixing bowl add butter and sugar. Beat on low speed until light and fluffy, about 3 minutes.
Beat in eggs and vanilla extract, scraping sides of the bowl with a spatula.
Slowly fold in flour, graham crackers crumbs and cornstarch and mix until combined.
Remove cookie dough from mixing bowl and place it on a floured working area. Pull the dough together and knead gently until it's not crumbly. With a floured rolling pin, roll out dough and with a cookie cutter, cut out cookies. I used a 3” cookie cutter. Place cookies on the prepared cookie sheets. Re-roll any trimming and cut out more cookies.
To make sure cookies keep their form during baking, refrigerate cut-out cookies for 10-15 minutes.
Bake cookies 15 - 20 minutes or until edges just beginning to turn golden brown.
Remove from the oven and let cool completely on baking sheets.
Once cool, spread marshmallow creme on one side of half the cookies. Sandwich a plain cookie on top of the marshmallow cream.
Make the ganache: Combine chocolate chips in a heat-proof bowl. Set aside.
Heat the heavy cream in a quart-sized, microwavable container and microwave for 3 to 4 minutes on high, or until it just begins to simmer; be careful not to allow cream to boil over. Pour the cream over the chocolate and let stand for 2 minutes. Stir well until smooth and glossy. Use as is for glazing. Spoon over sandwiched cookies. Refrigerate in a covered container.
Notes
Keep refrigerated in an airtight container.Makes about 12 moon pies.