Whisk condensed milk, green food coloring and peppermint extract in a bowl; set aside.
Beat the heavy cream until stiff peaks form.
Pour condensed milk mixture into whipped cream and whip until incorporated.
Fold in chocolate chips.
Line a loaf pan with plastic wrap, hanging some over the edges on all sides.
Add Thin Mints in a single layer, breaking them into pieces to fill any big gaps.
Spread half of the peppermint whipped cream over the cookies, then top with another layer of cookies, then top with more whipped cream.
Repeat with another layer of cookies, then whipped cream until pan is full.
Cover the pan with plastic wrap and freeze for at least 6 hours.
Dip pan in warm water to loosen sides and un-mold.
Uncover the cake and run a thin knife around the edges to loosen.
Remove the springform ring; smooth the sides of the cake using an offset spatula.
Garnish the top with crushed Thin Mints and whipped cream.