Cook the gluten free pasta until tender as per the pack instructions. Drain the pasta.
In a medium saucepan, melt the butter, then stir in the gluten free flour, add the mustard, salt and pepper.
Slowly add the milk - we use soya milk. Stirring constantly.
Cook over a medium heat, stirring constantly until mixture boils. Reduce the heat to a simmer, but keep stirring constantly.
Gradually stir in the cheese. This will need to be whisked in so that it melts and incorporates into the sauce.
Add your macaroni and stir to combine.
Put the mixture into an ovenproof dish (or smaller ones if you want individual portions). Sprinkle the breadcrumbs over the top.
Place the dish into the oven on Gas mark 6 for 10 minutes or until the breadcrumbs are golden brown.