Preheat the oven. Heat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
Toast the seeds and almonds. Spread the sesame seeds, sunflower seeds, and sliced almonds on the prepared baking sheet. Toast for 5–10 minutes, stirring once halfway through, until lightly golden and fragrant. Watch closely to prevent burning.
Prepare the wet ingredients. Mash the bananas in a large mixing bowl until mostly smooth. Stir in the cashew butter and applesauce until well combined.
Add the dry ingredients. Mix in the rolled oats, quinoa flakes, salt, vanilla extract, and cinnamon until evenly incorporated.
Fold everything together. Add the toasted seeds, almonds, and cacao nibs, if using, and stir until everything is evenly distributed.
Let the mixture rest. Allow the mixture to sit for 10 minutes. This gives the oats and quinoa flakes time to absorb moisture, making the bars easier to slice after baking.
Transfer to the pan. Spread the mixture evenly into an 11 × 7-inch baking dish lined with parchment paper. Press it down firmly with the back of a spoon or spatula.
Bake. Bake for 30 minutes, or until the edges are lightly golden and the center feels set.
Cool and slice. Let the bars cool in the pan before slicing into squares or rectangles. Enjoy warm or chilled.