In a large heavy stock pot or Dutch oven, saute bacon until crisp. Set aside. Use the bacon grease to saute the onions, garlic, celery and carrots. I like to get my onions cooking first so they get a little more done. While the onions start cooking, I finish chopping the garlic, celery and carrots and add each as they are ready. If your bacon didn’t have much fat, you can add a little extra butter for sauteing. Cook until carrots are crisp tender, stirring occasionally. Do not brown.
Add broth and broccoli to stock pot.
Pulverize the dehydrated summer squash in a blender or food processor until it becomes a fine powder. Volume should reduce by about half. Add powdered summer squash to stock pot. If you don’t have dehydrated summer squash, you can either add more cornstarch or simply have a thinner soup.
Simmer until the broccoli is tender (with frozen broccoli, heat through), at least 10-15 minutes, to give the summer squash time to rehydrate and start to thicken the soup.
In a measuring cup or small bowl, mix enough cold water with the cornstarch to form a loose slurry (about an equal amount of water and cornstarch). Stir cornstarch slurry into simmering soup, taking care to mix thoroughly as you are adding so it doesn’t clump. Do not boil – that will make lumps more likely to form. As it cooks, the broth will thicken.
Once broth has thickened, add spices and cream. Heat gently, do not boil. Once heated, start adding cheese, mixing after each addition, until all the cheese has been added. Crumble the bacon into the soup to finish.