Preheat oven to 350°. Chop chocolate mints; reserve 3 Tbsp. chopped mints. Prepare brownie batter according to package directions for cake-like brownies, stirring remaining chopped mints into batter. Pour batter into a lightly greased 10-inch springform pan.
Bake at 350° for 25 minutes or until a wooden pick inserted in center comes out with a few moist crumbs. Cool completely in pan on a wire rack (about 1 hour).
Meanwhile, let ice cream stand at room temperature 20 minutes or until slightly softened. Spread over cooled crust in pan. Freeze 3 hours or until firm.
Remove sides of pan. Let pie stand at room temperature 10 minutes before serving. Top with reserved chocolate mints.