Base: In a medium bowl mix together the biscuit crumbs, brown sugar and melted butter. Press into the bottom of an ungreased cake tin.
Bake for 8 to 10 minutes in preheated oven.
Topping: In a saucepan combine butter and brown sugar. Cook over moderate heat stirring constantly until mixture comes to a boil; boil for 1 minute. Pour immediately over baked base.
Bake for 10 more minutes. Remove from oven.
Sprinkle hot slice with chocolate chips. Let stand for 2 to 3 minutes until chips are shiny and soft. Spread the softened chocolate evenly over the top. Sprinkle with chopped nuts. Cool before cutting.