Preheat the oven to 220°C (425°F).
Spread the sweet potatoes on a tray and bake for 50 minutes or until soft.
Prepare the crumb in a small bowl and set aside.
Remove the skin from the sweet potatoes.
Add the roasted sweet potatoes to a large bowl with the milk, butter, maple syrup, salt, pepper and spices.
Whisk until creamy using an electric whisk.
Transfer the mixture into a baking dish.
Mix the topping ingredients together.
Scatter the topping over the sweet potato mixture.
Bake at 180°C (350°F) for 25–30 minutes or until golden and crisp.