Unwrap the Kit Kats and add to a food processor. Pulse until the mixture is fine crumbs. Add melted butter and pulse two more times.
Spray a tart pan with cooking spray, line the bottom with parchment paper and spray one more time. Press the mixture into the tart pan covering the entire bottom and spread up the sides. Chill for 1 hour.
Place milk chocolate chips in a glass bowl and set aside. Heat heavy cream in a sauce pan over medium high heat until it starts to bubble. Cover the chocolate chips with the hot heavy cream. Let sit for a minute, then whisk until smooth.
Let the chocolate ganache cool for about 20 minutes, then pour mixture into chilled Kit Kat shell. Chill tart for 4 hours. Garnish with a couple more Kit Kats.