Add the eggplant to a large rimmed baking sheet, then drizzle with the olive oil and sprinkle with the salt, red pepper and garlic. Toss to combine, then spread in an even layer. Bake for about 15 to 20 minutes, stirring once halfway through, until tender. Remove from the oven and set aside to cool slightly.
Decrease the oven temperature to 350ºF.
Meanwhile, add the walnuts to the bowl of a food processor and process until finely ground--but don’t go so far that it turns into a paste--then add them to a large bowl. Fold in the breadcrumbs, flour, shallot, parsley, oregano, basil, ricotta and spinach; set aside.
Add the roasted eggplant to the bowl of the food processor. Pulse until the eggplant is chopped well, but there is still some texture. You don’t want to completely puree the mixture.
Transfer the eggplant to the large bowl and mix until well-combined. Add additional salt and red pepper to taste, then stir in the egg. Form the mixture into balls about 1 ½ inches in diameter. Place the meatballs on a parchment-lined baking sheet.
Bake the meatballs for about 25 to 30 minutes, until firm and lightly browned. Serve with marinara sauce.
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