Preheat the grill to medium high. Cook the pasta in boiling water for 4-5 minutes or until just under cooked. Drain and return to the pan.
Fry the onion for 2-3 mins, add the bacon lardons in a large saucepan for 3 minutes, add the sliced mushrooms and fry for another 3 minutes or until both are golden brown. Remove from the pan and set aside.
In the same pan, melt the soya spread. Beat in the flour until it forms a smooth paste. Remove from the heat and gradually beat in the milk until smooth. Return to the heat and bring to a simmer, stirring, until thick enough to coat the back of a wooden spoon.
Stir the dairy-free cheese (reserving a third for the top), mustard and into the sauce and season well. Pour over the pasta, bacon and mushrooms and stir together. Spoon into a 2-litre ovenproof dish. Mix together the breadcrumbs, remaining cheese, thyme and then sprinkle over the top of the pasta.
Drizzle with olive oil and bake under the grill for 8-10 minutes or until the top is golden and crusty and the filling is bubbling. Stand for 5 minutes before serving with a big green salad.
If you can't get gluten free breadcrumbs, make your own by blitzing gluten free bread.
Note: the new chilled Free From dairy range is currently available in a limited number of stores. This will increase over the coming weeks.
See more Dairy-free recipes
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.
In order to enjoy optimum flavour and quality, frozen items are best used within 3 months of their freezing date.