Preheat the oven to 180°C/360°F.
In a frying pan, add some olive oil and brown the carrots (peeled and cut into small pieces) with the butternut squash (peeled and cut into cubes). Add the orange zest, garlic clove and orange juice. Season with salt and pepper. Continue cooking for 20 minutes. The butternut squash will start to soften into a puree.
In a large salad bowl, use your fingers to mix the unsalted butter (cut into cubes), semi-wholegrain flour, hazelnut powder and Parmesan until you obtain a crumble.
Pour the vegetable mixture into an oven dish, sprinkle the crumble over the top and bake for 20 minutes.
Serve hot with a salad.