Double Chocolate Brownies With Caramel Frosting

2 (1-oz.) unsweetened chocolate baking squares
2 (1-oz.) semisweet chocolate baking squares
1 cup butter, softened
2 cups sugar
4 large eggs
1 cup all-purpose flour
½ tsp salt
1 tsp vanilla
¾ cup chopped, pecans, divided
¾ cup semisweet chocolate chips, divided
Caramel Frosting

Microwave chocolate squares in a small microwave-safe bowl at medium 1 ½ minutes or until melted.  Stir chocolate until smooth.
Beat butter and sugar at medium speed with an electric mixer until light and fluffy.
Add eggs, 1 at a time, beating just until blended after each addition.  Add melted chocolate, beating just until blended.
Add flour and salt, beating at low speed just until blended.  Stir in vanilla, ½ cup pecans, and ½ cup chocolate chips.  Spread batter into a greased and floured 13 x 9 inch pan.  Sprinkle with remaining ¼ cup pecans and ¼ cup chocolate chips.
Bake at 350° for 40 minutes or until set.  Cool completely on a wire rack.  Spread evenly with Caramel Frosting.  Yield:  32 brownies.

            Caramel Frosting

¾ cup butter
2 cups sugar
½ cup buttermilk
12 large marshmallows
1 T light corn syrup
½ tsp baking soda

Melt butter in a large saucepan over low heat.   Stir in sugar and remaining ingredients.  Cook over medium heat, stirring occasionally, 25-30 minutes or until a candy thermometer registers 234° (soft ball stage).  Remove from heat.  Beat at high speed 5 to 7 minutes or until frosting thickens and begins to lose its gloss.  Yield:  2 cups.