Preheat oven to 400°F (200°C). Meanwhile, toss sweet potatoes, carrots, cauliflower and celery root with 1 tbsp (15 mL) olive oil, thyme, salt and pepper. Place on a large parchment paper-lined baking sheet. Roast until vegetables are tender and golden, about 25 min.
Heat 1 tsp (5 mL) oil in a saucepan over medium heat. Add onions and cook until softened, about 3 min. Stir in tomato paste and cook, stirring for 1 min. Add broth and bring to a boil. Boil 2 min. Remove from heat and whisk in cheese until it melts. Add vegetables to cheese sauce and transfer to a greased casserole dish.
Combine oats, ground hazelnuts, flour, honey and remaining oil to form a crumble. Sprinkle crumble mixture on vegetables and bake until topping is golden brown, about 30 min.
We have updated our privacy commitment and are now collecting cookies to provide you with ads tailored to your interest across the internet. For more information about cookies and how to disable cookies, visit our privacy commitment.Learn more