Dice the red bell pepper into small, uniform pieces to ensure even cooking.
In a medium bowl, briskly whisk together the whole eggs and egg whites until the mixture is uniform and slightly frothy.
Heat the olive oil in a non-stick skillet over medium heat, then add the diced peppers and sauté for 3-4 minutes until they begin to soften.
Add the baby spinach to the skillet and toss gently for 1 minute until just wilted.
Pour the whisked egg mixture over the vegetables and let it sit for 20 seconds before gently folding with a spatula.
Continue to cook, stirring occasionally, until the eggs are set but still moist and fluffy.
Remove from heat and stir in the nutritional yeast, sea salt, and black pepper.
Transfer the scramble to a bowl and top with the fresh avocado slices before serving.