Favorite Summer Soup: Leek, Fennel, Onion And Potato - cooking recipe

Ingredients

2 leeks, chopped (cleaned well but just soaking in some water and letting the dirt or sediment settle to the bottom, 1)
3 large sweet onions, cut in half and thin sliced (4 cups approximately)
1/4 lb fennel bulb, and part of the stem the tender part close to the bulb (1/2 to 3/4 cup)
3 potatoes, peeled and diced fine (2 cups)
3 teaspoons garlic, minced
4 cups chicken stock or 4 cups broth
1/2 cup sherry wine
3/4 cup heavy cream
1/4 - 1/2 cup instant potato flakes
1 tablespoon kosher salt
1 teaspoon ground black pepper
1 dash grated nutmeg
1/4 cup fresh parsley, chopped fine (reserve some for a garnish)
1 teaspoon fresh thyme
1 teaspoon fresh rosemary, chopped fine
3 tablespoons butter
1 tablespoon olive oil
Balsamic Mushrooms
8 cremini mushrooms, cut in half
1/8 cup balsamic vinegar
1 tablespoon olive oil
1/2 teaspoon kosher salt
1/4 teaspoon ground black pepper

Preparation

Vegetables -- To a large pot, add the olive oil and butter and bring to medium heat. Add the garlic, then the leeks and fennel, onion slowly cook on medium heat until lightly golden brown, but not dark brown. Just a slow caramelizing works best for this.
Potatoes -- Add the potatoes and mix just to combine the flavors. Add the herbs and seasoning, (rosemary, thyme, parsley -- reserving some for a garnish, salt and pepper and nutmeg). Cook 5 minutes.
Sauce -- Add the sherry, to deglaze the pan slightly, then the chicken broth and mix well. Cook 30 minutes on a low simmer until the potatoes fall apart.
My trick -- Instant potato flakes. Rather than corn starch in soups to thicken -- I love potato flakes. Just add them in, nothing more. A instant light thickening with some taste. I like to add 1/4-1/2 cup. Just add to the broth and it will slightly thicken without a fake corn starch or flour taste.
Finish -- Add the heavy cream to finish it off. Just heat and season with any salt and pepper to taste.
If you want and I love these -- balsamic mushrooms, just toss in a baggie, the mushrooms, balsamic vinegar, olive oil, salt and pepper. Add to a cookie sheet topped with foil and roast at 450 for 10-12 minutes until golden brown. Just slice and then top the soup.
Well worth making it. A bowl of this, a salad, a fresh tomato panini anything. So good and comforting.