Preheat your oven to 375°F (190°C). Lightly toast the breadcrumbs in a skillet with olive oil until golden and crispy, then set aside.
Toss chopped vegetables with thyme, cinnamon, salt, pepper, and melted butter. Spread them evenly in the bottom of your baking dish and roast in the oven for about 20 minutes until tender and fragrant.
Add sliced apples to the roasted vegetables along with the apple cider. Gently stir to combine and pour the mixture back into the oven for another 15 minutes, allowing the apples to soften and absorb flavors.
Remove the casserole from the oven and sprinkle the toasted breadcrumbs evenly over the top. This creates a crunchy contrast to the soft, bubbling layers beneath.
Return the dish to the oven and bake for an additional 10 minutes, until the topping is golden brown and the casserole is bubbling around the edges.
Let the casserole rest for a few minutes before serving. The layers will settle slightly, and the top will stay crispy, inviting you to scoop out hearty portions that combine soft vegetables and sweet apples with a crunchy topping.