Pumpkin and Mustard Greens Colcannon Soup

Here's the soup I made for yesterday's church dinner.  Colcannon is an Irish dish with mashed potatoes and cabbage, and this is loosely based on a recipe by Crescent Dragonwagon who wrote my favorite cookbook.  But I added pumpkin puree, which I make up from the pumpkins the kids bring home in the fall even if they're not pie pumpkins, and mustard greens from our garden.  It had a sharp, tangy flavor from the mustard but the sweetness of the pumpkin takes some of the nip out of it.  It's great comfort food on a cold day.

Here's my recipe: assume "approximately" in front of every ingredient, because I didn't measure.

1 1/2 C chopped onions
2 T butter
1 bunch mustard, washed thoroughly to remove bits of cedar scales and dirt, and sliced into ribbons (you could use frozen greens such as spinach, kale, or collards instead)
4-5 potatoes, peeled and diced
6-7 cups water (you could use chicken or vegetable stock, but I didn't)
2 cloves garlic
4 C pureed pumpkin or squash
salt to taste (I used about 2 t.)
pepper to taste
red pepper to taste (I used Aleppo pepper from Penzey's spices; omit if you don't want too much spice)
1-2 C milk
1/2 C cream

Saute onions until clear in butter: add mustard and saute if fresh: otherwise add water and mustard, potatoes, and garlic; bring to a simmer and cook for 20 minutes until potatoes are soft.  Add pumpkin and puree with immersion blender or in batches in a regular blender; leaving it chunky is also an option.  Add salt and pepper to taste; shortly before serving add milk and cream and heat just until hot.