if your pumpkin is still frozen throw it in a big pot with the milk, broth cubes, and half the can of tomatoes, bring to a boil and simmer until the pumpkin is thawed.
with a potato masher or an immersion blender, mash/blend the pumpkin and tomatoes in, it doesn't have to be perfectly smooth.
add rest of ingredients and simmer until onions are soft and flavors blended.