Preheat oven to 350°. Bake pecans in a single layer in a shallow pan 6 to 8 minutes or until lightly toasted and fragrant.

Microwave chocolate and butter in a large microwave-safe bowl at HIGH 1 to 1 1/2 minutes or until melted and smooth, stirring at 30-second intervals. Whisk in sugar and eggs until well blended. Stir in flour. Spread batter into a greased 13- x 9-inch pan.

Bake at 350° for 25 to 30 minutes or until a wooden pick inserted in center comes out with a few moist crumbs. Sprinkle warm brownies with toasted pecans and marshmallows.

Prepare Chocolate Frosting. Pour over pecans and marshmallows; spread to edges. Let cool 1 hour on a wire rack. Cut into squares.

Chocolate Frosting

1/2 cup butter

1/3 cup milk

6 tablespoons unsweetened cocoa

1 (16-oz.) package powdered sugar

1 teaspoon vanilla extract

Preparation

Cook first 3 ingredients over medium heat in a large saucepan, stirring constantly, 4 to 5 minutes or until butter melts. Remove from heat, and beat in powdered sugar and vanilla at medium speed with an electric mixer until smooth.