In a large skillet cook the onion and the garlic in 5 tbsp of olive oil over low heat, stirring occasionally, until the onion is softened. Add the eggplants and cook the mixture, stirring occasionally, for 8 minutes, or until the eggplants are softened. Stir in the zucchini and the bell peppers and continue cooking over low heat for 12 minutes. Stir in the tomatoes for 5 to 7 minutes.
In a large pan, melt the butter over medium-low heat. Add the gnocchi and sauté for 5 minutes. Transfer the gnocchi to a plate, add the vegetables ratatouille, a few leaves of baby spinach, and serve.