The original recipe for these ultra decadent brownies comes from Bon Appetit January 2007. I made a few small changes because I liked them with a little more peanut butter frosting.
Brownies
3/4 c unsalted butter (1 1/2 sticks)
7 ounces bittersweet chocolate, chopped
3 ounces unsweetened chocolate
1 1/2 c sugar
1 1/2 tsp vanilla extract
1/4 tsp salt
4 large eggs
1 c all purpose flour
1 c roasted salted peanuts, chopped
butter for lining pan
Frosting
1 1/2 c chunky peanut butter (do not use natural or old-fashioned)
6 Tablespoons (3/4 stick) butter
1 c powdered sugar
2 T whole milk
1 tsp vanilla extract
1/8 tsp salt
1/8 tsp cinnamon
Ganache
4 ounces semisweet chocolate, chopped
3 ounces bittersweet chocolate, chopped
4 Tablespoons (1/2 stick) butter
Prepare brownies
Preheat oven to 325° F. Line 13x9x2" metal baking pan with foil leaving an overhang. Butter foil. Place 3/4 cup butter in large saucepan. Add 7 ounces of bittersweet and 3 ounces of unsweetened chocolate and melt over low heat until smooth. Remove from heat and whisk in sugar, vanilla, salt, and then eggs, one at a time. Fold in flour and then stir in peanuts. Pour into prepared pan and bake on center rack about 30-35 minutes. Tester should have moist crumbs attached. Let cool on wire rack before frosting.
Prepare frosting
Beat peanut butter and butter with an electric mixer until smooth and light. Beat in powdered sugar, salt, cinnamon, then milk and vanilla. Spread over cooled brownies.
Prepare ganache
In a small saucepan melt semisweet and bittersweet chocolate and butter until smooth. Pour and spread over frosted brownies.
Chill brownies until set, about 1 1/2 hours. Can be made a day ahead, just cover and keep chilled.
*Helpful hints
I find it easiest and fastest to spread ganache with a large offset spatula.
Also, don't try to cut brownies when they are too cold or the ganache will crack and break apart from frosting. I let mine sit about ten or fifteen minutes at room temperature and that did the trick.

