1. Heat oven to 350°F. Grease 13x9x2-inch baking pan.
2. Combine flour and brown sugar in large bowl. Cut in butter until mixture resembles coarse crumbs. Add egg; mix well. Stir in 1-1/2 cups chocolate chips and nuts; set aside 1-1/2 cups mixture.
3. 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.
4. Bake 25 to 30 minutes or until golden brown. Top with reserved toffee bits. Cool completely in pan on wire rack. Cut into bars. About 24 bars.