Position an oven rack into the middle of the oven and preheat to 350°F. Optional: Lightly rub the inside of 9-inch springform pan with cold butter. Cut out a piece of parchment paper the same size as the pan bottom and place inside the pan.
Prepare the crust. Grind the graham cracker crumbs in the food processor working in 2 to 3 batches, transferring the crumbs to a medium bowl once crushed. Alternatively, you can crush the graham crackers in a sealed plastic bag with a rolling pin. Melt the butter and with a fork stir the graham cracker crumbs while slowly pouring the melted butter over the crumbs.
Once all the crumbs are 'wet' with butter, transfer to the springform pan into an even layer. Using the bottom of a measuring cup, water glass, or with your hands, press the crumbs into the pan starting in the center and working towards the edges. Push to crumbs up the sides as you go.
Bake the crust for 6 to 8 minutes. Let cool for 3 to 5 minutes. While the pan is still warm, wrap the outside of the pan with plastic wrap. Place two pieces of plastic wrap in opposite directions making a 't' with the warm pan still in the center and carefully bring plastic wrap up the sides so it seals to the outside. Alternatively, you can skip this step and use extra wide aluminum foil or a crock pot bag to wrap the pan for the water bath. Cool the crust completely before filling with cheesecake batter.
Prepare the filling. In a standing mixer with the paddle attachment or in a large bowl with a hand mixer, beat the cream cheese until creamy about 2 minutes. Scrape down the sides and bottom of the bowl. Add the sugar into the cream cheese and mix until fully incorporated, scraping down the sides and bottom of the bowl.
On low speed, mix in the vanilla, mint extract, corn starch. Add the eggs, one at a time, followed by the green food dye. Raise the speed to medium and mix until the ingredients are well incorporated, about 1 minute, scraping down the sides and bottom of the bowl when needed.
Mix in the mini chocolate chips on low speed and pour the batter to the prepared crust. Transfer the pan to a water bath in a roasting pan or bakinbg dish large and deep enough to hold it. Pour very hot water into the roasting pan so that it covers 1-inch of the sides of the pan or just below where you wrapped with pan.
Bake in 350°F oven for 1 hour 15 minutes - do not open the oven door during baking. The cheesecake will be done when the outer edges are firm and the center jiggles just slightly. After baking, turn off the heat, crack the oven with a kitchen towel or wooden spatula and let the cheesecake cool for 1 hour in the oven.
Remove the foil and wrap from the outside of the pan. Run the dull side of a knife around the outside of the crust to release it from the pan. Transfer the whole pan to the fridge and chill for at least 4 hours or overnight.
For the ganache. In a small saucepan, bring the heavy cream to just a simmer. Pour over the mini chocolate chips in a small bowl. Let sit 5 minutes then whisk until smooth. Let cool 20 to 40 minutes depending on the thickness you want, at 20 minutes the ganache will still be thin and pour easily and at 40 minutes the ganache will be thick and spreadable.