Slow Cooker Spinach Pasta Primavera

8 oz short pasta penne, rotini, or shells

3 cups broth vegetable or chicken

1 cup heavy cream or half-and-half

1 cup Parmesan cheese grated, divided

3 cups fresh spinach loosely packed

1 cup broccoli florets chopped small

1 cup carrots thinly sliced

1 cup bell peppers sliced

1/2 cup frozen peas

1 cup cherry tomatoes halved

3 cloves garlic minced

1 small onion chopped

2 tbsp olive oil or butter melted if butter

1 tsp Italian seasoning

1/2 tsp dried basil optional

salt to taste

black pepper to taste

red pepper flakes pinch, optional