Preheat your oven to 350°F and lightly grease an 8x8-inch baking dish with coconut oil.
In a large mixing bowl, mash the bananas thoroughly with a fork until they reach a smooth, liquid consistency.
Remove the pits from the Medjool dates and finely dice them before stirring them into the banana mixture.
Pour in the liquid egg whites, vanilla extract, ground cinnamon, and sea salt, whisking until the ingredients are fully combined.
Slowly add the vanilla protein powder, folding it in with a spatula until no dry clumps remain and the batter is thick.
Transfer the batter into the prepared baking dish, spreading it out evenly to the edges.
Top the batter with the chopped walnuts and sliced almonds, pressing them down slightly so they adhere.
Bake for 22 to 25 minutes until the center is set and a toothpick comes out clean.
Let the bars cool completely in the pan for at least 20 minutes before slicing into 5 rectangular bars.