Peanut Butter Cup Brownies

I've been trying to recreate a brownie I've gotten at a local Dairy. I think this one comes pretty close. Everyone who has had one so far has said they are great!

Peanut Butter Cup Brownies
Peanut butter and chocolate layers borrowed from Sunday Baker

Brownie Layer:
1 Betty Crocker 9x13 family size box brownie mix
Ingredients called for on the box

Peanut Butter Layer:
1 cup creamy peanut butter
1/2 stick unsalted butter, room temperature
3/4 cup powdered sugar
1/8 teaspoon salt
1/8 teaspoon ground nutmeg
1 tablespoon whole milk
1 teaspoon vanilla extract

Chocolate Layer:
7 oz. semi-sweet chocolate-can use chocolate chips
1/2 stick unsalted butter

Topping:
Chopped Reese's peanut butter cups, frozen

Preheat oven to 350. Bake brownies as directed on box. Cool completely.

Using electric mixer, beat peanut butter and 1/2 stick butter in medium bowl to blend. Beat in powdered sugar, salt, and nutmeg. Then add milk and vanilla. Spread frosting over cooled brownies. Put into fridge for an hour or two to cool and set this layer.

Chop frozen peanut butter cups into small pieces. Set aside while you melt the chocolate layer.

Melt 7 oz. chocolate and 1/2 stick butter in microwave until smooth. Spread chocolate ganache over the cooled peanut butter, smoothing as you go. Sprinkle frozen peanut butter cups over the chocolate. Press in to set.

Chill until set, about 1 1/2 hours. Cover and keep chilled.