Melt the butter in a large pot over medium heat until it foams, then add the onion, carrots, and celery. Sauté for 5 minutes, stirring often, until the vegetables begin to soften and look glossy.

Add the garlic and cook for 1 minute, stirring constantly to avoid browning. You should smell the garlic sharply and see no dark spots.

Whisk in the all-purpose flour and cook for 1-2 minutes, stirring until it forms a smooth paste. The mixture should look slightly thicker and lightly toasted.

Gradually whisk in the chicken broth until fully combined and smooth. Whisking constantly will prevent lumps while the pot starts to steam and thicken.

Add the diced chicken, dried thyme, and dried parsley, then stir to coat the chicken in the broth. Let the soup return to a steady simmer.

Simmer for 15 minutes, stirring occasionally, until the chicken is cooked through and the vegetables are tender. Keep the bubbles gentle rather than boiling hard.

Stir in the heavy cream and nutmeg, then bring the soup back to a gentle simmer. Watch for steam and small bubbles around the edges, not a rolling boil.

Add the egg noodles and cook for 6-8 minutes until tender, stirring occasionally to prevent sticking. They should be fully cooked but still hold their shape.

Season with salt and pepper to taste, then garnish with fresh parsley. Serve immediately while the broth is hot and silky.