Place a piece of kitchen string on a work surface. Stack the thyme sprigs on top. Tie string around thyme sprigs and tie in a knot. Set aside.

In a large Dutch oven or soup pot, combine the cauliflower, potatoes, carrots, celery and chicken broth, bay leaves, thyme bundle, garlic salt, onion powder and kosher salt. Stir to bury the thyme bundle and bay leaves.

Bring the mixture to a boil then cover and reduce to a steady simmer. Cook for 20 minutes or until vegetables are nice and tender.

While the soup is cooking, combine the soft butter and the flour in a small-size bowl. Stir with a small spatula or the back of a spoon until all of the flour is incorporated. You should have a thick, smooth paste. Set aside.

When the veggies are tender, remove the bay leaves and thyme. Scoop out 3 cups of the broth and vegetables and place in a blender container. Remove the center of the blender top off and cover the opening with a small funnel or several thicknesses of paper toweling.

Blend until the mixture is smooth then return it to the soup pot. Add the milk and chicken and stir to combine. Bring the mixture to a very low simmer then add the Beurre Manie (butter-flour mixture) in teaspoonfuls, while stirring. Add the cheese and stir until melted. Taste and add more salt if needed. Serve with a garnish of fresh thyme leaves and a sprinkling of freshly ground black pepper.