Gardener's Cottage Pie - Testing

If shepherds were vegetarian, what would they make their pies from? This is a recipe I'd started exploring about 5 years ago and lost the finalized instructions for. The following are the ingredients, I think...
1 - It needs something. After the fact, I added cheddar, which worked nicely. I'm also wondering how mushrooms would change things, and if it's a question of cheddar OR mushrooms, or a matter of cheddar AND mushrooms.

Topping
1½ lbs. boiled, peeled and mashed potatoes 
2 Tbsps. butter
2 Tbsps. cream
salt, to taste
OPTIONAL dash of turmeric 

1. Mash all together until well blended

Filling

3 Tbsps. veg oil

2 onions, diced (12oz/340gr)

1 leek, sliced
4 garlic cloves, minced (20gr)
2 carrots, diced (6oz) 
½ cup white wine
2 1 red bell pepper, diced
OPTIONAL 3 stalks (about 4.5 oz) diced celery
8 oz mushrooms diced
1 large tomato or 8oz diced canned tomato
1 cup corn

1 cup peas 
1 bunch spinach or swiss chard, sliced thin
1 zucchini, diced
½ tsp pepper
1 tsp paprika

1 tsp basil

1 tsp thyme

1 tsp hot sauce

½ cup (2oz) grated cheddar
½ tsp salt
1 cup veg stock (?)
Hot sauce, to serve

1. Sauté onion, leeks and garlic in the oil until starting to soften.
2. Add the carrots, sauté 2 minutes, then add wine. Cover and steam for 4 minutes
3. Add the sauté pepper and mushrooms and cook a few minutes before stirring in the tomato, corn, peas, spinach and zucchini. Cover and cook for about 5 minutes.
4. Mix in the cheese, salt, pepper, paprika, basil, thyme, and hot sauce.
5. Spoon into a casserole and top with the potato mix.
6. Bake 30 minutes at 400°F.