Place the diced eggplant in a colander. Sprinkle with 1 teaspoon of salt and toss to coat. Let it sit for 20-30 minutes to draw out moisture. Meanwhile, preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper.

After 20-30 minutes, firmly squeeze the eggplant in batches to remove as much liquid as possible. Pat dry with paper towels. Transfer the dried eggplant to the prepared baking sheet, drizzle with 1 tablespoon of olive oil, and toss to coat. Spread in a single layer.

Roast the eggplant for 15-20 minutes, or until very tender and lightly browned. Remove from the oven and let cool slightly. Once cool enough to handle, transfer to a large mixing bowl and mash thoroughly with a potato masher or fork until a smooth, paste-like consistency is achieved. There should be no large chunks.

While the eggplant is roasting, heat the remaining 1 tablespoon of olive oil in a skillet over medium heat. Add the finely diced yellow onion and sauté for 5-7 minutes until softened and translucent. Add the minced garlic and red pepper flakes (if using) and cook for another minute until fragrant. Remove from heat.

Add the sautéed onion and garlic mixture to the mashed eggplant in the large mixing bowl. Stir in the panko breadcrumbs, grated Parmesan cheese, beaten egg, chopped fresh parsley, dried oregano, and black pepper. Mix everything thoroughly until well combined. The mixture should be firm enough to shape. If it's too wet, add another tablespoon or two of breadcrumbs. If too dry, a tiny splash of water.

Using wet hands or a small scoop (about 1.5 tablespoons), roll the mixture into 1-inch to 1.5-inch meatballs. Place them on the same parchment-lined baking sheet, leaving a little space between each.

Bake for 20-25 minutes, flipping halfway through, until the meatballs are golden brown and firm to the touch. The internal temperature should reach at least 165°F (74°C).

While the meatballs are baking, gently warm your marinara sauce on the stovetop over low heat.

Serve the Tender Eggplant Meatballs immediately with warm marinara sauce. Garnish with fresh basil, if desired. They are excellent with pasta, in a sub roll, or simply as an appetizer.