Preheat oven to 300°F. Spray a 12-cup muffin tin generously with non-stick cooking spray, making sure to coat the sides well so the bites release easily after baking.

In a blender, combine egg whites, cottage cheese, and half the Monterey Jack cheese. Blend on high for 30 seconds until completely smooth and slightly frothy. This step is what creates that signature fluffy, custardy texture.

Squeeze excess moisture from the chopped spinach using a clean kitchen towel - this prevents soggy bites. In a bowl, toss together the dried spinach, roasted red peppers, feta, garlic powder, salt, and pepper.

Divide the spinach mixture evenly among 6 muffin cups (you'll use every other cup for better heat circulation). Pour the blended egg white mixture over the fillings, filling each cup about three-quarters full. Top with remaining Monterey Jack cheese.

Bake for 22-25 minutes until the centers are just set and no longer jiggly. The tops should be lightly golden and slightly puffed. They will deflate as they cool - this is normal.

Let cool in the pan for 5 minutes, then run a thin knife around each bite to loosen. Remove carefully and serve warm, or cool completely on a wire rack for meal prep storage.