Preheat your oven to 400°F and line a large baking sheet with parchment paper.
In a shallow dish, whisk the egg whites until slightly frothy. In a second shallow dish, combine the almond flour, grated parmesan, garlic powder, oregano, sea salt, and black pepper.
Dip the chicken breast into the egg whites, ensuring it is fully coated, then dredge it through the almond flour mixture, pressing firmly so the breading adheres to all sides.
Place the breaded chicken on one side of the prepared baking sheet.
On the other side of the sheet, toss the broccoli florets with olive oil and a small pinch of salt, spreading them out into a single layer.
Bake for 15 minutes. Carefully remove the tray from the oven and spoon the marinara sauce over the chicken, then sprinkle with the shredded mozzarella.
Return the tray to the oven and bake for another 5 to 8 minutes, or until the chicken is cooked through to 165°F and the cheese is melted and bubbly.