• Preheat oven to 350 degrees. Lightly spray a 9 x 13" pan with non-stick spray. Set aside.
• In a large mixing bowl, combine the sugar, flour and salt. Set aside.
• In saucepan, add butter, oil, cocoa powder, and water. Over medium heat melt the ingredients together stirring often. Once everything has melted together, remove from heat. Pour the hot chocolate liquid over the dry ingredients. Mix together with a large whisk or hand mixer.
• Dissolve baking soda in the buttermilk. Stir together until the buttermilk becomes foamy. Pour the buttermilk into the cake batter mixture. Add in the eggs and vanilla. Whisk or mix together until all ingredients are well incorporated and smooth. Pour the batter into the prepared pan.
• Bake for 30-35 minutes. To test for doneness, insert a toothpick into the center of the cake. If the toothpick comes out clean and crumb-free, the cake is done. Let cake cool completely to room temperature before frosting.

For the Peanut Butter Frosting:

• Using a hand or stand mixer, cream together the peanut butter and room temperature butter. Add in the vanilla extract and salt. Mix to combine.
• A half cup at a time, gradually add in the powdered sugar, stopping the mixture to scrape down the sides of the bowl with a rubber scraper. Add in the milk to achieve a creamy texture.
• Spread the peanut butter frosting over the cooled cake using an offset frosting spatula.
• Cut cake into squares and enjoy.