1. Preheat oven to 350�F. In a large bowl, mix together flour, sugar, cocoa, baking soda, and salt. Whisk in oil, vinegar, 1 tsp vanilla, and 2 cups cold water until well blended
. 2. Pour into 2 greased 9-inch round cake pans, dividing evenly. Bake 25 to 28 mins, or until a cake tester inserted in center comes out clean. Let cakes cool in pans 15 to 20 mins, then unmold onto racks to cool completely
. 3. Meanwhile, in a 2-qt bowl, combine cream, semisweet chocolate chips and milk chocolate chips. Heat in a microwave on High 1 1/2 to 2 mins, or until melted and smooth when stirred. Stir in remaining 1 tsp vanilla
. 4. Remove 3/4 cup chocolate mixture and set aside to cool. While remaining mixture is still warm --but not hot --add Snickers pieces and stir until combined (some pieces will remain chunky; some will melt). Set aside to cool
. 5. When firm enough to spread, fill stacked cake layers with half of Snickers mixture. Spread remaining mixture evenly over top of cake. Frost sides with some of reserved 3/4 cup chocolate mixture and spread remaining chocolate mixture over top of cake. Sprinkle peanuts around top edge of cake to make a border. Refrigerate for at least 1 hour before serving.