Heat oven to 350°F.
Grease 13x9x2-inch baking pan.
Combine flour and brown sugar in large bowl.
Cut in butter until mixture resembles coarse crumbs.
Add egg; mix well. S
tir in 1-1/2 cups chocolate chips and nuts; set aside 1-1/2 cups mixture.
Press remaining crumb mixture onto bottom of prepared pan.
Bake 10 minutes.
Pour sweetened condensed milk evenly over hot crust; set aside 1/4 cup toffee bits.
Sprinkle remaining toffee bits over sweetened condensed milk.
Sprinkle reserved crumb mixture and remaining 1/2 cup chips over top.
Bake 25 to 30 minutes or until golden brown.
Top with reserved toffee bits.
Cool completely in pan on wire rack.
Cut into bars.