Stir together first 5 ingredients in a large mixing bowl.
Add butter, stirring until mixture is crumbly. Reserve half of mixture (about 2 3/4 cups). Press remaining half of mixture into bottom of a lightly greased 13- x 9-inch pan.
Sprinkle evenly with chocolate morsels, and, if desired, pecans.
Microwave caramels and half-and-half in a microwave-safe bowl at MEDIUM (50% power) 3 minutes. Stir and microwave at MEDIUM 1 to 3 more minutes or until mixture is smooth.
Let stand 1 minute.
Pour evenly over chocolate morsels.
Sprinkle evenly with reserved crumb mixture.
Bake at 350 for 30 minutes or until light golden brown. Cool in pan on a wire rack.