Preheat oven to 350 degrees. In a large food storage bag, add pretzels and seal. Crush into small pieces with a rolling pin or heavy spoon.
Add pretzel crumbs to 9x13 pan and drizzle with 5 tablespoons melted butter. Stir to combine and then press onto the bottom of the pan to form the crust. Set aside.
In a large bowl, melt 3/4 cup butter. Stir in cocoa, water, sugar, vanilla, banana, and eggs. Stir in flour, baking powder, and salt until just combined.
Pour brownie batter on top of pretzel crust and carefully spread to edges.
Bake for 20-25 minutes or until the brownies are set. Let the brownies cool completely.
In a medium bowl, add Nutella and whipping cream and microwave for one minute.
Whisk together and then spread on top of cooled brownies.
Refrigerate 3-4 hours prior to serving. The longer the brownies are refrigerated, the more set the ganache will be.
Sprinkle with crushed pretzels, and ENJOY!