These are good.
10 Tablespoons unsalted butter, cut into cubes
2 cups dark brown sugar
1 cup smooth and natural peanut butter
2 teaspoons vanilla
1/2 teaspoon salt
2 cups flour
1 teaspoon baking powder
Preheat oven to 325 degrees F. Grease a 9x13 inch pan and line with parchment. Grease the parchment paper too.
In a medium saucepan over medium heat, melt butter and sugar until the butter is just melted. Remove from the burner and allow to cool for 5 minutes, then add the peanut butter. Stir until incorporated. Allow to cool for 5 minutes more, then whisk in the eggs and vanilla extract. You want the sugar, butter, and peanut butter mixture to be cool enough that the eggs won't cook when they're added in.
Whisk together salt, flour, and baking powder. Add dry ingredients all at once to the wet. Stir until just incorporated. Pour the thick batter in the prepared pan and smooth out. Bake for 20-25 minutes, or until a skewer inserted in the center of the blondies comes out clean. Remove from the oven and allow to cool to room temperature before frosting.
Milk Chocolate Frosting
6 Tablespoons unsalted butter, at room temp
3 Tablespoons cocoa powder
1/4 teaspoon salt
1 1/2-2 cups powdered sugar
3 Tablespoons milk
3/4 cup milk chocolate chips, melted
In the bowl of a stand mixer, beat together the butter, cocoa powder, and salt. Add 1/2 cup powdered sugar followed by 1 Tablespoon milk. Beat well. Add another cup of powdered sugar, followed by 2 tablespoons of milk. Add the melted and slightly cooled chocolate chips to the frosting and beat to incorporate. Add the final 1/2 cup of powdered sugar if you need a bit for thickness. Spread evenly over cooled peanut butter blondies.