Preheat the oven to 350°F (175°C) and line an 8x8 inch square baking pan with parchment paper.

In a large mixing bowl, whisk together the mashed bananas, peanut butter, maple syrup, egg, and vanilla extract until the mixture is homogenous.

Sift in the cocoa powder and baking soda to prevent clumping, then add the salt and stir until fully incorporated.

Fold in the chocolate chips using a rubber spatula.

Transfer the batter into the prepared pan and smooth the surface with a spatula.

Evenly distribute the crushed pretzels over the top, pressing them lightly into the batter to ensure they adhere.

Bake for 22 to 25 minutes, or until the edges are firm and a toothpick inserted into the center comes out with only a few moist crumbs.

Remove from the oven and allow to cool completely in the pan for at least 30 minutes to let the structure set before slicing.