Add the squash and water. If you want the soup to be on the thicker side, add three cups of water. If you want it to be looser, add all four cups of water. Season with salt and pepper to taste.
Let simmer for 30 minutes on low heat.
Remove soup from heat. With a hand immersion blender, blend soup, being carful not to over blend. There should still be some vegetable chunks in the soup.
Set soup aside.
Preheat oven to 350 degrees F.
For the croutons, place multigrain bread pieces on a baking sheet. Drizzle with EVOO, melted butter, and salt. Toss the bread pieces with your hands until every piece is evenly coated. Bake for approximately 15 minutes, or until crispy and golden brown.