Frosted Peanut Butter Blondies

I made these bars this weekend and J and I quite enjoyed them. I added semi-sweet chocolate chips and butterscotch chips (about a 1/2 cup of each) to the bar batter. The butterscotch was a little much and overpowered the peanut butte. J actually thought there was too much frosting. Too much frosting. What? Yeah, not changing the frosting amount. Anyways, next time I think I'll do semi-sweet chocolate chips and peanut butter chips instead to really boost that peanut butter flavor.

Peanut Butter Blondies with Milk Chocolate Frosting

adapted from recipe by joythebaker.com

10 Tablespoons unsalted butter cut into 5 cubes
2 cups dark brown sugar (I think you could use light too)
1 cup smooth peanut butter
2 eggs
2 teaspoons vanilla extract
1/2 teaspoon salt
2 cups flour
1 teaspoon baking powder

Preheat oven to 325 degrees F. Grease a 9x13-inch pan, line with parchment paper if you have it on hand, then grease the parchment paper. If you don't have parchment paper, these blondies will be just fine.
In a medium saucepan over medium heat, melt butter and sugar together 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 begin to cook when they're added in.
Whisk together salt, flour and baking powder. Add dry ingredients all at once to the wet ingredients. Stir until just incorporated. Pour the thick batter into 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, softened
3 Tablespoons unsweetened 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. Melt milk chocolate chips in the microwave or in a double boiler. Add melted and slightly cooked milk chocolate the frosting and beat to incorporate. Add the final 1/2 cup of powdered sugar if you need a bit more thickness. Spread evenly over peanut butter blondies.