Preheat oven to 350 degrees.
Lightly steam carrots and cauliflower if using fresh, not frozen cauliflower, until vegetables are just tender. Be careful not to overcook. Drain water.
Add remaining frozen vegetables to the pot with the carrots and cauliflower, and add 1/4 cup of fresh water, plus 1/4 teaspoon salt and 1/8 teaspoon garlic powder to the pot.
Bring vegetables to a boil, and cook for about 3 minutes, just until they are thawed.
Drain vegetables, reserving cooking liquid.
Place vegetables in a casserole dish, or 9 x 13 inch glass baking pan.
In a medium saucepan, melt butter, and stir in flour. Mix well over medium-high heat, and let the butter-flour mixture cook for 1 minute.
Put the milk in a measuring cup and add some of the cooking water to make 2 cups.
Slowly whisk in milk and vegetable cooking water until sauce is smooth. Continue to whisk until sauce comes to a boil, and thickens. Reduce the heat to low, and add wine, salt, thyme, garlic powder and nutmeg.
Add cheeses and stir well to combine and melt.
Remove sauce from heat, and adjust any seasonings as needed.
Pour sauce over the vegetables.
Toss the fresh breadcrumbs with the 1 tablespoon of olive oil, in a medium bowl.
Sprinkle bread crumbs over the sauce.
Bake for about 30 minutes, until the sauce is bubbly, and breadcrumbs are light golden brown.
If necessary, brown the breadcrumbs under the broiler for the last minute or two.