Boil the Water: Fill a large pot with water and bring it to a boil while preparing the tomato and bean mixture.
Sauté the Aromatics: Heat the olive oil in a large skillet or sauté pan over LOW heat. Add the diced onion and minced garlic, then cook for 3 to 4 minutes, stirring occasionally, until the onion is soft but not browned and the garlic is very fragrant. Build the Tomato Mixture: Add the fire-roasted diced tomatoes, rinsed and drained cannellini beans, Italian seasoning, salt, black pepper, and crushed red pepper flakes to the skillet. Increase the heat as needed to bring the mixture to a low boil. Simmer the Beans: Cover the skillet with a lid and reduce the heat to LOW. Let the tomato and bean mixture simmer for 5 minutes. Cook the Gnocchi: Once the water reaches a rapid boil, add about 1 tablespoon of salt, if desired. Add the potato gnocchi and cook for 3 to 4 minutes, or until the gnocchi floats to the surface. Drain the Gnocchi: Drain the cooked gnocchi well in a colander.
Combine the Ingredients: Remove the skillet from the heat. Add the drained gnocchi, fresh baby spinach, and 2 tablespoons of the grated Parmesan to the tomato and cannellini bean mixture. Wilt the Spinach: Stir everything together gently until the spinach is slightly wilted and the ingredients are evenly combined.
Finish and Serve: Sprinkle the remaining Parmesan over the top and garnish with fresh basil leaves. Serve immediately with additional Parmesan on the side.
