Cook the pasta, strain and place to one side. Peel and chop the sweet potatoes before boiling them in a pan of hot water for 10 minutes until soft.
Strain the potatoes into a bowl.
Gently crush the potatoes with a fork and season with salt, pepper, paprika, cinnamon, dried herbs and stir in the maple syrup.
Melt the butter in a saucepan and whisk in the flour and soya milk. Heat while stirring until the sauce thickens and then stir in the cheese until it has melted.
Pour the pasta into your serving dish and crumble the feta cheese on top. Stir in the wholegrain mustard and cheese sauce. Grate a little more cheese on top and sprinkle with rosemary before baking for 30 minutes at 180'C.