Heat oven to 350*. Arrange crackers in single layer in ungreased 15x10x1 inch baking pan. Melt butter in medium saucepan over medium-high heat. Stir in brown sugar. Bring to a boil. Boil 2 minutes. Remove from heat. Stir in pecans. Pour and spread over crackers. Bake 10 minutes. Cool 30 minutes or until cooled.
Crush crackers into coarse crumbs. Sprinkle half of crumbs in bottom of ungreased 13x9x2 glass baking dish. Cut and remove carton from dulce de leche ice cream. Cut ice cream into 1/2 inch thick slices. Arrange slices over crumbs, overlapping slightly. Spread ice cream with spatula until even, pressing down firmly. Freeze 1 hour or until firm.
Place hot fudge ice cream topping in resealable 1 quart plastic bag. Cut small hole in bottom corner of bag with topping. Squeeze bag to pipe fudge topping over ice cream. Scatter remaining half of praline crumbs over fudge layer. Freeze 30 minutes or until fudge is firm.
Cut and remove carton from coffee ice cream. Cut ice cream into 1/2 inch thick slices. Arrange slices over crumbs, spreading ice cream until smooth; press down firmly. Freeze while preparing topping.
Beat whipping cream in large bowl until stiff peaks form. Fold in liqueur. Spread over top of dessert. If desired, garnish with chocolate curls. Freeze 4 hours or until firm. Let stand at room temperature for 20 to 30 minutes before serving.