Preheat the oven to 425°F. Line a rimmed baking sheet with foil and fit it with a wire rack. Spray the rack with oil.
Pat the chicken breasts dry. Season them on both sides with kosher salt, black pepper, and garlic powder.
In a shallow bowl or a Pyrex baking dish, whisk the egg with a tablespoon of water.
In another shallow bowl, mix together the almond meal and Parmesan.
Dip each chicken breast in the egg, then dredge it in the almond meal mixture. To avoid a sticky mess, use one hand for the egg mixture and one hand for the almond meal mixture.
Transfer the coated chicken breasts to the prepared wire rack. Spray their tops with olive oil. Bake them for 15 minutes.
Remove the pan from the oven, but keep the oven on. Top each chicken breast with 2 tablespoons of marinara sauce and one slice of provolone.
Return the chicken breasts to the oven for 5 more minutes, until they are cooked through, their internal temperature reaches 165°F, and the cheese is melted.
Transfer the chicken to plates, top it with chopped basil or parsley, and serve.
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Notes
If your chicken breasts are larger than 6-7 ounces each, you'll need to bake them for 20-25 minutes (their internal temperature should reach 165°F). If that's the case, loosely cover them with foil after the first 15 minutes to protect them from burning.
You can keep the leftovers in a sealed container in the fridge for 3-4 days. Reheat them in a 350°F oven until heated through. Reheating in the oven is better than using the microwave because it helps re-crisp the almond meal.