• Heat the olive oil in a large pot or Dutch oven over medium heat. Add the sliced leeks, 1 teaspoon of salt and ½ teaspoon of ground black pepper. Saute until fragrant and translucent, about 5 minutes.
• Add minced garlic, stir and cook for 1 more minute.
• Add the zucchini and vegetable stock, bring to a boil over high heat, then reduce heat back to medium and let it simmer actively until all the vegetables are soft, about 10 minutes.
• Stir in the parsley and simmer 5 more minutes.
• Turn off the heat and puree the soup with a stick blender (or using a standard blender with the center of the lid removed and a tea towel over the top to let steam safely escape).
• Pour in the cream if using, stir, taste and season with more salt and pepper to your preference. Serve while hot with parsley or croutons for garnish.

Croutons

• Toss the bread cubes with the melted butter in a large skillet over medium heat. Toss or flip every few minutes until lightly browned and crispy on the sides but still a little soft in the middle. Season with a pinch of salt if desired.