Put the instant pudding mix, milk, mint extract and food coloring in a large bowl and mix until well combined and thickened, about 2 minutes. Fold in the whipped topping and chocolate chips, then set aside.
Prepare a half sheet pan by lining it with plastic wrap, allowing excess wrap to hang over the sides. Place half of the graham cracker halves onto the prepared sheet pan so they are almost touching. Pour the filling to the center of the graham crackers and disperse it with the back of a spoon, spreading it to the edge of the graham crackers. Top the filling with the remaining graham cracker halves. Fold the plastic wrap over the sandwiches and transfer the sheet pan to the freezer until the filling is frozen, at least 1 hour.
Unwrap, lift out of the pan with the plastic wrap and transfer to a cutting board. Using a knife, cut between the graham crackers, making individual sandwiches. Serve immediately or wrap individually and return to the freezer to eat another day.