In a skillet, saute onions in a tablespoon of extra virgin olive oil over medium-high heat until browned for 20 minutes. When ready, transfer the onions to a paper towel-lined bowl to cool.

While onions cook, dice grape tomatoes. Whisk 2 teaspoons of olive oil, lemon juice, and garlic in a small bowl, combining well. Place spinach in a large bowl, then pour over with the marinade, tossing to coat. Transfer spinach to a baking dish and distribute in an even layer. Next, add tomatoes into the large bowl (where the spinach was) and stir to coat with residual marinade lightly. Set aside.

When onions have cooled, stir in mascarpone until well combined. Season chicken with salt and pepper. Spoon a few tablespoons of onion onto the chicken, then roll up with eggplants and place seam-side down on top of the spinach. Lightly spray with cooking spray, then sprinkle with basil. Repeat as necessary.

When all meat and eggplant have been prepared, scatter with tomatoes. Bake the rollatini at 400 degrees Fahrenheit for 20 minutes, broil for the remaining 5 to 10 minutes, and cook until browned. When ready, immediately plate and serve.