Preheat oven to 325 degrees F. Grease 9x13-inch baking pan.

In small microwave-safe bowl, combine chopped baking chocolate and 1/2 cup butter. Microwave on high power 30 seconds. Stir well. Continue heating 30 seconds at a time until chocolate is melted and mixture is smooth. Set aside.

In medium bowl, whisk together eggs and sugar. Add in flour and salt. Mix well.

Stir the chocolate mixture and vanilla extract into the egg mixture. Stir until well combined.

Pour brownie batter into greased pan. Bake 30 minutes, until edges begin to slightly pull away from the sides of the pan. Remove from oven and allow brownies to cool completely.

In medium bowl using a hand mixer, mix together the butter and peanut butter for the filling. Slowly add in powdered sugar. Mix until completely combined.

When brownies are completely cool, press peanut butter filling into an even layer on top of the brownies. Refrigerate at least 30 minutes.

In small microwave-safe bowl, combine chopped baking chocolate and butter for the glaze. Microwave on high power for 30 seconds then stir well. Microwave in 15-second intervals until chocolate mixture is smooth.

Drizzle melted chocolate over peanut butter filling. Use back of spoon to spread chocolate to edges. Refrigerate 30 minutes until chocolate firms up.