Preheat oven to 350°f and line an 8 x 8-inch baking dish with parchment paper. Make the brownie layer by using a hand mixer on high to cream the softened butter with the sugar for 2-3 minutes. Add the eggs and vanilla and use the hand mixer on low until combined. Mix in flour, cocoa powder, and salt and transfer to your prepped baking dish, using a spatula to push the brownie batter to meet all four corners. Bake for 30-35 minutes, until a toothpick comes out clean. allow to cool for at least 30 minutes before moving to the next step. Make your peanut butter fudge layer by beating together softened butter, creamy peanut butter, and powdered sugar until smooth. Spread the peanut butter fudge mixture on top in an even layer. Make the ganache layer by adding the chocolate chips and heavy cream to a microwave-safe bowl. microwave on high for 2 minutes. use a whisk to combine until smooth. Pour the ganache over the peanut butter layer and use a spatula to spread it across in an even layer. place in the refrigerator to cool and set for at least 2 hours before slicing and serving.