peanut butter "brownies"

this is probably the least healthy thing i have ever made, so if you make them, make sure there will be lots of peanut butter lovers around to eat these before you do, because they're incredible. these are more like chocolatey blondies than brownies (see picture, taken from smitten kitchen):

peanut butter brownies
adapted from smitten kitchen
makes roughly 24 brownies, depending on how you cut them

for brownies:

• 2 sticks (1/2 pound) butter, softened
• 1 3/4 cups sugar
• 1 cup creamy peanut butter
• 2 large eggs plus 1 large yolk
• 2 teaspoons pure vanilla extract
• 2 cups all-purpose flour
• 1 1/2 cups semisweet, bittersweet or dark chocolate chips (9 ounces)
• 1/2 teaspoon salt*
  

for ganache:

• 1 1/2 cups semisweet, bittersweet or dark chocolate chips (9 ounces)
• 1/2 cup heavy cream
• 1 tbsp unsalted butter, softened

*if you're using conventional peanut butter, like jiffy or skip, etc., you probably won't need to add salt. if you're using all-natural peanut butter, it tends to have slightly less salt, so you might need to add some in. test the batter and see what you think.

make brownies: preheat oven to 350° F with rack in middle. line the bottom of a 13"x9"x2" baking pan with parchment paper, then grease paper and sides of pan.

beat together butter and sugar with an electric mixer at medium-high speed until mixture is light and fluffy, then add peanut butter and beat until incorporated. beat in whole eggs, egg yolk, and vanilla. reduce mixer speed to low, then mix in flour until just combined.

mix in chocolate chips (1 1/2 cups) then spread batter in baking pan, smoothing top. it will be thick, almost like cookie batter. bake until brownies are deep golden, puffed on top and a wooden pick inserted in center come out with some crumbs adhering, 40 to 45 minutes. cool completely in pan, about 1 1/2 hours.

make ganache: put chocolate chips (1 1/2 cups) in a heatproof bowl. bring cream to a boil in a small saucepan, then pour over chocolate chips and let mixture stand for one minute. gently whisk in butter until it is incorporated, chocolate is melted, and a smooth mixture forms. (i found that the boiling cream alone wasn't enough to fully melt the chocolate chips, so i stirred them for a few minutes in a double boiler after adding the cream, and then stirred in the butter.) spread ganache on cooled brownies and let stand until set, about 15 minutes.