6tablespoonsunsalted butter(3 ounces), room temperature and cut into small pieces
1teaspoonvanilla extract
½heavy cream
2.5cupspowdered sugar(10 ounces)
Instructions
For the cake:
Preheat oven to 350 degrees and prepare 3 eight-inch round or square cake pans by greasing and flouring the pans and then set aside
Combine and sift the flour, baking powder, and salt in a small bowl and set aside
Add the brown sugar and butter to the bowl of a standing mixer and mix on medium speed until pasty
Drizzle in the oil and mix on medium speed for 5 minutes; scrape down the bowl intermittently to ensure everything is mixed well.
Add the peanut butter and stir to combine on low speed
Add eggs one at a time, and mix until incorporated
Add the flour mixture in 3 parts to the mixer alternating with the milk in 2 parts, beginnining and ending with the flour; do not overmix. Mix only until flour has been incorporated
Divide batter evenly among the 3 pans and bake for 28 to 33 minutes
When finished, remove cakes and cool in the pans for 30 minutes and then invert on wire rack to finish cooling right side up
For the ganache
Pour chocolate into a heatproof bowl
Heat the heavy cream in saucepan over medium heat until simmering; promptly remove, pour over semi sweet chips, and cover with dish or lid to trap the heat for approximately 5 minutes
Remove cover and stir well beginning in the center of the mixture
Allow the mixture to cool for 3 to 4 hours to thicken (unless you would like to use it as a glaze in which case it will be ready in about an hour)
For the frosting
Combine the peanut butter and butter in the bowl of a standing mixer and mix on medium speed for about 2 to 3 minutes
Slowly add remaining ingredients and continue mixing until fluffy, about 3 to 4 more minutes.
Frosting will keep at room temperature for 3 days or refrigerator for 7
To assemble the cake
Ensure that ganache and frosting have thickened to the appropriate spreading consistency (use the refrigerator to speed up the process)
If the frosting has been refrigerated for more than 1 hour or so, you may have to rewhip the frosting, and if the ganache has become to stiff, simply place it somewhere warm to soften.
Assemble the cake by covering each layer with a thin layer of ganache followed by one third of the frosting, then top with next layer