Prepare all the vegetables and ingredients by chopping, slicing, and draining as needed.
Heat olive oil in a large 6-8 quart pot over medium heat and add chopped onions, carrots, celery, and garlic; season generously with salt and pepper, then cook until they soften, about 4 to 6 minutes.
Pour in the vegetable broth, diced tomatoes, tomato paste, Italian seasoning, and crushed red pepper; increase heat to bring the mixture to a boil.
Add kidney beans, great northern beans, green beans, and pasta to the pot, stirring well; reduce heat and let it simmer partially covered for 8 to 10 minutes, stirring every couple of minutes to prevent sticking.
Stir in the zucchini slices, fresh spinach, and chopped parsley, then simmer for an additional 2 minutes; adjust seasoning with salt and pepper to taste before serving warm.