Preheat oven to 350°.
Place cookies in large bowl and crush into small pieces with a small mallet, or place them in a zip bag and crush with a rolling pin, then place in large bowl. Stop when pieces are smaller than a dime but not yet crumbs.
Pour melted margarine over cookies in bowl and mix until all cookie pieces are well coated. Press in bottom of ungreased 9x13 baking pan.
Place sweetened condensed milk and 1 cup of the mini chocolate chips in a microwave safe bowl and heat until melted together (30 seconds at a time with stirring in between until smooth). Pour over cookie crust. Sprinkle remaining chocolate chips over top.
Bake 10 minutes.
Cool in refrigerator at least 2 hours before cutting.
Makes 24 bars