Make the Cornmeal Croutons
Preheat your oven to 350°F / 175°C.
Grease one very large or two standard baking sheets.
In a medium bowl, lightly beat the egg.
Stir in the corn muffin mix, shredded cheese, and milk until just combined.
Drop the mixture by scant teaspoonfuls onto the prepared baking sheet(s) to create small mounds. Lightly sprinkle with freshly ground black pepper and a pinch of coarse sea salt, if desired.
Bake for 12 to 14 minutes, or until the croutons are golden brown.
Remove from the baking sheet and let them cool completely on a wire rack while you prepare the soup.
Make the Tuscan Bean Soup
In a large saucepan or Dutch oven, heat the oil over medium heat.
Add the sliced leek and cook until tender, stirring occasionally.
Add the quartered mushrooms, chopped sweet pepper, and minced garlic to the pan.
Cook for 5 minutes more, stirring occasionally, until the vegetables have softened.
Pour in the water, undrained tomatoes, rinsed cannellini beans, salt, and black pepper.
Stir everything together and bring the soup to a boil.
Reduce the heat and let the soup simmer, uncovered, for 5 minutes to allow the flavors to meld.
Stir in the fresh baby spinach and cook for just a minute or two until it has wilted.
Serve the soup immediately, topped generously with the cooled Cornmeal Croutons.
