Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Place the chicken breast between two sheets of plastic wrap and pound with a meat mallet to an even 1/2-inch thickness.
In a shallow bowl, whisk the egg until smooth. In a separate shallow bowl, combine the almond flour, parmesan, oregano, garlic powder, salt, and pepper.
Dip the chicken breast into the egg wash, letting the excess drip off, then press firmly into the almond flour mixture until evenly coated on both sides.
Place the coated chicken on one side of the prepared baking sheet.
On the other side of the sheet, toss the broccoli florets with the olive oil and a pinch of extra salt and pepper.
Bake for 15 to 18 minutes, or until the chicken reaches an internal temperature of 165°F and the broccoli is tender-crisp.
Remove from the oven and spoon the marinara sauce over the chicken, then top with the shredded mozzarella.
Switch the oven to the broil setting and return the pan to the oven for 2 to 3 minutes until the cheese is bubbly and golden brown.
Let the chicken rest for 2 minutes before serving alongside the roasted broccoli.