Heat oven to 250°F. Line a baking sheet with a cooling rack and set aside.

Spread grated zucchini on a plate or baking sheet double-lined with paper towels. Cover with more paper towels and let drain for at least 30 minutes.

Stir bread crumbs, ricotta, scallions, herbs, flour, egg, and salt in a medium bowl until well combined. Set aside. Squeeze zucchini to release as much liquid as possible. Add zucchini to the batter and mix well. Batter should be lumpy but hold together and spoon easily—if it feels loose, add 1 additional tablespoon of flour.

Heat 2 tablespoons of olive oil in a large, heavy-bottom skillet over medium-high heat. Scoop about ¼ cup batter per fritter and fry in batches, 3 or 4 at a time, depending on the size of your skillet. Cook fritters until golden-brown, about 2 minutes per side. If oil starts to smoke, turn heat down to medium and continue frying. Transfer fritters to the cooling rack and place in the oven to keep warm. Repeat with remaining batter, adding more oil as needed.

Sprinkle fritters with sea salt and serve immediately with warm marinara sauce, if desired.