1Heat oven to 350ºF. Grease bottom and sides of rectangular pan, 13x9x2 inches, with shortening; lightly flour. In medium bowl, mix flour, baking soda and salt; set aside.
2In large bowl, beat sugar and butter with electric mixer on medium speed, scraping bowl occasionally, until fluffy. Beat in eggs, one at a time, until smooth and blended. Add vanilla. Stir in melted chocolate. Gradually beat in flour mixture alternately with buttermilk, beating after each addition until smooth. Pour into pan.
3Bake 35 to 40 minutes or until toothpick inserted in center of cake comes out clean. Immediately poke top of cake all over with toothpick or fork. Mix condensed milk and caramel topping; spoon over warm cake, allowing it to soak in. Sprinkle chopped candy over cake. Place frosting in small microwavable bowl. Microwave uncovered on High 20 to 30 seconds or until pourable; drizzle over cake. Cool cake about 1 1/2 hours before serving.