Cook bacon until crispy. My preferred method is to lay out the bacon strips on a rimmed cookie sheet (I used 2 cookie sheets for this recipe). Place in a cold oven and turn the oven on the 400F. Around the time the oven is done preheating, the bacon is ready. Remove the bacon from the cookie sheet(s) and reserve the bacon grease. Once bacon has cooled, cut or crumble into large bacon bits.
Preheat oven to 375F (if you do this step immediately after cooking the bacon, it’s fine if your oven starts a little hot).
Cut your pumpkins in half. Scoop out the seeds. Place your pumpkin halves on a cookie sheet (I did it cut side up, but it doesn’t really matter). Bake for 35-45 minutes, until soft. Remove from oven and let cool.
Spoon pumpkin meat out of the peel. Mash with a fork or potato masher (this give a more uneven texture which is part of the rustic nature of this soup; you could also use a potato ricer or immersion blender for a finer-textured soup).
Heat 2-3 Tbsp of bacon grease in a medium stock pot over medium-high heat. Add diced onions and garlic and saute until onions are fully cooked and caramelized.
Add broth to de-glaze the pot. Add mashed pumpkin, nutmeg and 2-3 additional Tbsp of bacon grease (you want 4-5 Tbsp total; it’s a good idea to add a little less and then taste your soup and decide if you want add more).
Turn the heat down to medium-low and bring to a simmer.
Serve the soup by ladling into a bowl and generously topping with bacon bits.