This is the cake that people will pay you to make for them. True story. This cake is decadent, rich, and oh my, so indulgent. It’s a showstopper and will make you come back time and time again.

Note: This cake takes its time to come together. It may look daunting, but it can be broken down into two days if you don’t have the time to devote to it from start to finish. There’s been a number of times where I’ll bake the cake one day, place in the freezer, and then finish the frosting and glaze the following day. Either way, this cake is worth it. Trust me.

For the cake:

• 2 cups all-purpose flour
• 2 1/2 cups sugar
• 3/4 cup unsweetened cocoa
• 2 tsps. baking soda
• 1 tsp. salt
• 1 cup vegetable oil
• 1 cup sour cream
• 1 1/2 cups water
• 2 tbsps. distilled white vinegar
• 1 tsp. vanilla extract
• 2 eggs

Place the oven rack in the second from the bottom level of the oven. Preheat to 325 degrees. Grease/ butter the bottom and sides of three 9-inch baking pans. Line each pan with circled parchment paper and butter the tops of these as well.

In a large bowl, whisk together all the dry ingredients. Blend in the oil and sour cream, gradually incorporate the water and beat together. Blend in the vinegar and vanilla extract. Whisk in the eggs, blend well, and be sure to scrape down the sides of the bowl. Divide evenly amongst the three prepared pans.

Bake for 28-32 minutes or until toothpick comes out clean. Baking time varies by oven. I’ve discovered in my oven, I get the best results when I bake them for 24 minutes. Let the cakes cool in pans for 20 minutes before transferring to wire racks and place in the freezer to firm up for 30 minutes before proceeding with the frosting. These cakes are very soft and delicate. This is a good time to determine if you want to proceed with seeing the cake through to completion or waiting to finish the cake at a later date. I tend to make the cakes one day, freeze, and then frost the following day. So after freezing for 30 minutes, I remove them from the freezer and wrap them individually in plastic wrap, and place them back in the deep freezer.

Peanut Butter Frosting:

• 10 ounces cream cheese, at room temperature (I’ve used 8oz before & it turns out fine)
• 1 stick unsalted butter, at room temperature
• 5 cups powdered sugar, sifted
• 2/3 cup smooth peanut butter

In a large bowl, beat the cream cheese and butter until light and fluffy. Gradually add the powdered sugar 1 cup at a time and beating well after each addition, scraping the sides and bottom of the bowl down several times. After the final addition, beat on medium speed for 4 minutes. Add the peanut butter and blend thoroughly.

Take the frozen cake layers and assemble with equal parts of frosting between the layers. Coat the outside of the cake with a thin layer of frosting, creating a crumb coat. Return to the freezer for another 30 minutes. Once set, add the final layer of frosting, for a smooth, clean cover. Return to the freezer for another 20-30 minutes while you make the glaze as this will help with the drip effect of the glaze.

Chocolate Peanut Butter Glaze:

• 8 oz. semi-sweet chocolate
• 3 tbsps. smooth peanut butter
• 2 tbsps. light corn syrup
• 1/2 cup of half & half

In a saucepan over medium heat, combine chocolate, peanut butter, and corn syrup. Stir continually until chocolate is melted and smooth. Add in the half & half and whisk until smooth. While still warm, pour the glaze slowly over the top of the cake, allowing it to spill over the edges using an offset spatula to spread evenly over the cake to make drips.  Refrigerate the cake 30 minutes prior to serving. Serve with a tall, cold glass of milk.

Source: http://smittenkitchen.com/blog/2008/08/chocolate-peanut-butter-cake/