Heat oven to 350. Grease foil-lined 13 x 9 baking pan. Microwave chocolate squares and butter in microwavable bowl on high for 2 minutes or until butter is melted. Stir until chocolate is completely melted.
Stir sugar into chocolate until well blended. Mix in eggs. Stir in flour.
Spread 1/2 of the batter in baking pan.
Bake 25 minutes or until batter is firm to the touch.
Meanwhile, microwave caramels and cream in a microwavable bowl on high for 3 minutes or until caramels begin to melt.
Whisk until smooth.
Stir in 1 cup of pecans (you can use walnuts if you like). Gently spread caramel mix over brownie batter in pan. Sprinkle chocolate chips, if desired.
Pour remaining unbaked brownie batter evenly over caramel mix, sprinkle with remaining nuts. (some of the caramel mix may peak through).
Bake an additional 30 minutes. Cool in pan.
Run knife around edge of pan to loosen brownies from the sides. Lift from pan using foil as handles.