Slow Cooker Zucchini Soup

INGREDIENTS

1 1/2 lb

sweet Italian sausage

2 cups

1/2-inch pieces celery

2 lb

zucchini, cut into 1/2-inch slices

2 28 ounce cans

diced tomatoes

green bell peppers, cut into 1/2-inch slices

1 cup

chopped onion

2 tsp

salt

1 tsp

white sugar

1 tsp

dried oregano

1 tsp

Italian seasoning

1 tsp

dried basil

1/4 tsp

garlic powder

6 tbsp

grated Parmesan cheese, or to taste