Pulse cremini mushrooms in clean, dry food processor until pieces are no larger than ¼ inch, 5 to 7 pulses; transfer to bowl. Pulse eggplant, onion, and garlic in now-empty processor until chopped fine, 6 to 8 pulses; transfer to bowl with mushrooms. You can also dice the mushrooms, eggplant and onion.

Heat a 12-inch nonstick skillet over medium heat until balls of water dances on surface like mercury balls. Add processed vegetables and ground mushrooms to hot pan. Cook and stir until vegetables have released their liquid, about 5 minutes. Uncover, increase heat to medium-high, and cook until vegetables are well browned, about 15 minutes. Add 2 tablespoons of water to deglaze the pan and transfer mixture to a large bowl.

Add protein crumbles, breadcrumbs, parsley, Bragg’s Amino Liquids, nutritional yeast, Italian dried herbs, and aquafaba to bowl with browned vegetables and toss to combine. Using your hands, knead the mixture well until cohesive and sticky, about 1 minute.

Shape the mixture into meatballs (36 1½-inch balls or 18 3-inch balls) and space evenly on prepared sheet. Bake until browned and firm, 20 to 30 minutes, gently turning meatballs and rotating sheet halfway through baking.

Meanwhile, bring 4 quarts water to boil in large pot. Add pasta and 1 tablespoon salt and cook, stirring often, until al dente. Drain pasta and return it to pot. Measure out 4 cups sauce and toss with pasta to combine. Top individual portions of spaghetti with meatballs and sprinkle with remaining ¼ cup basil.

Serve, passing remaining sauce separately.