Preheat oven to 400 degrees.
Heat olive oil and butter in a skillet.
Add zucchini, garlic, carrots, celery, onions, mushrooms and squash. Cook for 5 minutes until golden.
Add sprigs of thyme, salt and pepper.
Sprinkle the vegetables with Carbquick or flour. You can usewhatever flour you prefer, depending on your dietary restrictions. If you arenot on a low-carb diet, you can use regular all-purpose flour or a gluten-freeflour alternative. They all have the same effect for this purpose.
Stir the vegetables and flour mixture and cook for several minutes.
Stir in the broth, milk and sour cream. Cook until the sourcream is incorporated and the mixture becomes thick.
Stir in 1/4 cup white cheddar cheese.
Transfer the mixture to a greased baking dish.
Top with white cheddar, Parmesan and breadcrumbs.
Bake in the oven 20 minutes. Allow to rest for 5 minutesbefore serving.