1) For the soup: Combine the 8 to 10 slices stale white bread and cold water to cover in a small bowl. Let sit until bread is soaked, about 5 to 10 minutes. Squeeze water from bread, set bread aside, and discard water.
2) Combine the almonds, garlic, and salt in a large-sized food processor. Process until the almonds are completely ground.
3) Add the soaked bread; process till smooth.
4) With the motor running, gradually add the oil, then the vinegar. Process, stopping to scrape the sides of the bowl occasionally, until the mixture is smooth.
5) Add the 2 cups of broth, and blend again until smooth.
6) Pour the mixture into a large bowl, and stir in the cold water, adding more for a thinner soup, if desired. Store in the refrigerator until ready to serve.
7) For the garnish: Drizzle the bottom of a large baking sheet with 1 tablespoon of the olive oil. Toss the bread cubes with the remaining olive oil, and place them on the baking sheet. Bake in a preheated 350°F oven for about 30 minutes, until the cubes are crisp and light golden brown.
8) To serve: Remove the soup from the refrigerator and stir a few times to make sure all the elements are combined. Ladle it into bowls, and top with generous amounts of croutons and green grapes.