Preheat your oven to 350°F (175°C). Grease a 9×13 inch baking pan and set aside.

In a large bowl, mix the melted butter and sugar until fully combined. Add in the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

In a separate bowl, sift together the flour, cocoa powder, and salt. Slowly add this mixture to the wet ingredients, stirring until well combined.

Pour the brownie batter into the prepared baking pan and spread evenly. Bake in the preheated oven for about 25 minutes, or until a toothpick inserted comes out with moist crumbs.

In a medium bowl, combine the peanut butter, powdered sugar, and vanilla extract. Mix until smooth and creamy.

Once the brownies have cooled, spread the peanut butter filling evenly over the top.

In a small saucepan, heat the heavy cream until just boiling. Pour the hot cream over the chocolate chips in a bowl and let it sit for a couple of minutes. Stir until smooth.

Drizzle the chocolate ganache over the peanut butter layer. Allow everything to set for at least 30 minutes before serving.