PREHEAT oven grease and flour cake pan.

Line bottom of pan with parchment paper. Microwave 1 cup of the chopped chocolate and the butter in large microwaveable bowl on high 2 min. or until butter is melted.
Stir until chocolate is completely melted. Add sugar; mix well. Blend in eggs and vanilla.
Add flour and salt; stir until well blended.
Pour into prepared pan. Bake until toothpick inserted in center comes out with fudged crumbs.

(Do not over bake.)

Cool in pan 5 min. Run small knife around side of pan to loosen cake. Invert cake onto serving platter. Remove and discard waxed paper. Cool cake slightly. Microwave caramels and milk in medium microwaveable bowl on high 2 min. or until caramels begin to melt. Stir until caramels are completely melted.
Sprinkle marshmallows and remaining chopped chocolate over torte.
Drizzle with caramel mixture.