• Gather all ingredients and measure everything before you begin.

For the Beans:

• If using dried beans, place them in a large bowl with 4 tablespoons kosher salt and the baking soda. Cover with cold water by several inches, stir to dissolve, and let soak at room temperature overnight.
• Drain and rinse the soaked beans thoroughly. Transfer to a pressure cooker or a large pot with the bay leaves and the whole garlic clove. Cover with water by about 1 inch, add a generous pinch of salt, and cook until tender—about 25 minutes at high pressure, or roughly 1 hour at a gentle simmer on the stove. Discard the bay leaves and reserve some of the bean cooking liquid to adjust the soup’s consistency.
• If you prefer to use canned beans, drain and rinse several cans and skip the soaking and long simmer; reserve some canning liquid or use water as needed when finishing the soup.

For the Soup:

• In a large pot or Dutch oven, warm the olive oil over medium heat. Add the sliced garlic and red pepper flakes and cook, stirring, until the garlic just begins to color, about 1–2 minutes—take care not to burn it.
• Add the escarole and 4 cups of water to the pot. Bring to a boil over high heat, then lower the heat and simmer gently until the escarole has completely softened, about 20 minutes.
• Stir in the drained cooked beans and continue simmering until some beans begin to break down and the broth thickens slightly, about 15 minutes. If the soup becomes too thick, thin it with reserved bean cooking liquid or additional water to reach your preferred texture.
• Taste and adjust seasoning with salt and plenty of freshly ground black pepper.
• To serve, place toasted croutons in bowls, ladle the hot soup over them, and finish each portion with a drizzle of olive oil and an optional sprinkle of grated Parmigiano-Reggiano.