Finely grind cookies in processor. Blend in melted butter. 

Press crumb mixture evenly onto bottom and 2 1/4 inches up sides of 9x2 3/4-inch springform pan.Refrigerate 30 minutes.

Meanwhile, soften mint ice cream slightly, about 2 minutes in microwave set on medium-low or in refrigerator. 

Spread mint ice cream evenly in chilled crust. Freeze until set but not solid, about 1 hour. 

Soften cookies and cream ice cream. Spread evenly over mint ice cream in pan.

Melt chocolate chips in top of double boiler over simmering water, stirring until smooth.

Using fork, lightly drizzle some chocolate back and forth over cake, creating design. 

Release sides of pan. Cut cake into wedges. 

Serve, passing remaining melted chocolate chips separately as sauce.