Add 3 cups of broth, bring to a boil, and then lower to a simmer. Cover and let simmer for 10 minutes.
Let cool for a few minutes and then place in a blender. Blend on medium speed until desired texture.
Add back to pot and season with salt and pepper to taste.
For the croutons: Heat a medium-sized pan on medium heat.
Completely butter one side of each slice of bread.
Place two slices of bread, buttered side down, in the pan.
Add the shredded cheese. Then top each slice with another slice of bread, buttered side up.
Turn heat to low and cook 3-4 minutes, until golden brown.
Flip and cook for another 3-4 minutes, until golden brown. Cheese should be fully melted.
Remove from heat, and cut into one inch pieces (if you wish, you can cut the crust off before slicing the croutons). Serve immediately alongside the soup.
Recipe by Six Snippets at https://www.sixsnippets.com/cauli-broccoli-soup/