Chocolate-Peanut Butter Fun Cake

Ingredients

• 1 teaspoon baking soda 
• 1.8 ounces bittersweet chocolate chopped
• 0.8 cup cocoa powder unsweetened
• 0.3 cup creamy peanut butter 
• 0.3 cup egg whites (from 2 large eggs)
• 1.3 cups flour all-purpose
• 16 servings kosher salt 
• 0.3 cup pinenuts unsalted dry chopped
• 0.5 cup sugar 
• 6 tablespoons butter unsalted chilled cut into 1/4" cubes ()
• 1.5 teaspoon vanilla extract 
• 0.3 cup vegetable oil 

Equipment

• bowl
• frying pan
• sauce pan
• baking paper
• oven
• knife
• whisk
• wire rack
• blender
• hand mixer

Directions

1. Preheat oven to 350°F. Coat bottom and sides of pan with nonstick spray; line bottom of pan with parchment paper.
2. Whisk flour and next 4 ingredients in a large bowl.
3. Add oil, vanilla, and 1 1/4 cups water; whisk until smooth. Fold in chopped chocolate.
4. Scrape into prepared pan; smooth top.
5. Bake until a tester comes out clean when inserted into center, 35-40 minutes.
6. Let cool completely in pan on a wire rack.
7. Combine sugar and egg whites in a medium metal bowl set over a saucepan of simmering water.
8. Whisk constantly until sugar dissolves and mixture is hot to the touch, 3-4 minutes.
9. Remove from heat; usingan electric mixer, beat on high speed until cool and thick, 5-6 minutes. Beat in vanilla, then peanut butter. With mixer running, add butter a few pieces at a time, beating to blend between additions. Season with salt.
10. Run a thin knife around pan to release cake. Invert cake onto a serving plate.
11. Spread peanut butter buttercream over top.
12. Garnish with chopped chocolate and peanuts. DO AHEAD: Can be made 1 day ahead. Store airtight at room temperature.
13. Cut into 2" squares.