makes about 12 bars

1/2 cup butter, at room temperature

1 1/2 cups sugar

2 eggs

2 teaspoons vanilla extract

1 1/4 cups all purpose flour

1/4 teaspoon salt

3 tablespoons cocoa powder

2/3 cups chocolate chips (optional)

1 1/2 cups creamy peanut butter

1/3 powdered sugar

1 3/4 cups crushed pretzel pieces

6 tablespoons butter, melted