1. Prep Eggplant: Preheat your oven to 375°F (190°C) and line two large baking sheets with parchment paper. In a very large pan or skillet, combine the cubed eggplant and vegetable broth. Bring to a strong simmer over medium-high heat, then reduce heat to low. Cook for 12-15 minutes, stirring occasionally, until the liquid thickens and the eggplant is soft but not mushy. Using a slotted spoon, transfer the cooked eggplant to a large bowl. Discard any remaining liquid and wipe the pan clean.
2. Rehydrate Mushrooms: While the eggplant cooks, place the dried mushrooms in a medium bowl and cover them with very hot tap water. Let them soak for 15 minutes. Afterward, transfer them to a cutting board and chop them roughly. Keep ⅓ cup of the soaking liquid for later.
3. Sauté Aromatics: Heat 2 tablespoons of olive oil in the same pan over medium-high heat. Add the diced onion, celery, and minced garlic. Season with a good pinch of salt and pepper. Cook for 5-7 minutes, stirring occasionally, until the vegetables are lightly browned. Stir in the chopped mushrooms and cook for another 2-3 minutes. Pour in the reserved ⅓ cup mushroom liquid and scrape up any browned bits from the bottom of the pan. Transfer these sautéed contents to the bowl with the eggplant.
4. Combine Ingredients: Add the breadcrumbs, chickpeas, oregano, fresh basil, fresh parsley, egg, 2 teaspoons of Kosher salt, and ½ teaspoon of black pepper to the bowl with the eggplant and sautéed vegetables. Stir well with a spatula until all ingredients are completely combined.
5. Process Mixture: Transfer half of the eggplant mixture to a food processor. Pulse until the mixture is finely chopped but still has some texture, not a complete puree. It will be sticky but should hold together like traditional meatballs. Repeat with the remaining mixture.
6. Form & Bake Meatballs: Using a large cookie scoop (about 2 tablespoons), form 24 meatballs and place them evenly onto the two prepared baking sheets (12 meatballs per sheet).
7. Bake & Serve: Bake for 20 minutes, then rotate the pans from front to back and top to bottom for even cooking. Continue baking for another 15 minutes, or until the tops are lightly browned and the meatballs feel firm when gently pressed. Serve immediately with your favorite spaghetti and marinara sauce, or let them cool on wire racks before refrigerating or freezing.