Preheat your oven to 375°F (190°C). In a large mixing bowl, combine the chopped root vegetables with a pinch of salt, pepper, and dried thyme. Toss everything together until the vegetables are evenly coated.
Spread the seasoned vegetables evenly in a buttered baking dish, creating a single layer for even cooking.
In a separate bowl, whisk together the creamy secret ingredient and shredded cheese until smooth and well combined.
Pour the creamy mixture over the vegetables, gently stirring to coat all the pieces thoroughly.
Sprinkle the bread crumbs evenly over the top of the casserole, then drizzle with melted butter for crispy browning.
Bake in the preheated oven for about 40 minutes, or until the top is golden brown and bubbling around the edges.
Remove from the oven and let it rest for a few minutes; this allows the casserole to set and makes serving easier.
Slice into portions and serve warm, enjoying the creamy, crispy, and tender textures of this seasonal dish.