Peel the carrots and onions, then cut them into large pieces. Clean the leek and cut it into sections. Set these vegetables aside. Remove the germ from the garlic cloves and lightly crush them.

Place the veal pieces evenly in a large pot. Add 3 liters of cold water, thyme sprigs, bay leaf, carrots, onions, and leek. Heat gently and let simmer over low heat for about 1 hour 30 minutes.

Meanwhile, clean and slice the mushrooms. Heat a skillet with sunflower oil over high heat and sauté the mushrooms until golden. Set aside.

Once the meat is cooked, remove it along with the vegetables from the pot and set aside. Strain the broth through a fine sieve to remove impurities.

In a large saucepan, melt the butter over medium heat. Add the flour and whisk to form a roux. Cook for a few minutes, stirring constantly.

Gradually pour the strained broth into the roux while whisking until you obtain a smooth, slightly thick sauce. Let it simmer for a few minutes over low heat, then stir in the heavy cream.

Return the cooked veal and sautéed mushrooms to the sauce, and let simmer for a few more minutes to allow the flavors to blend together.