Step 1

Finely slice the onions. Get a frying pan over a medium heat. Melt a third of the butter in the pan. Add the onions with a good pinch of salt. Cook, stirring occasionally until completely collapsed, soft and caramelised. This will take around 30 minutes.

Step 2

Once the onions are cooked, pour in the white wine and add the thyme, stripping the leaves from the stalks straight into the pan. Leave to bubble away by half then take the pan off the heat. The onions can be done in advance and kept in the fridge.

Step 3

Cook the macaroni in a large pan of boiling salted water for 2 minutes less than packet instructions. Drain once ready.

Step 4

Meanwhile make the cheese sauce. Melt the remaining butter in a large saucepan over a medium heat. Once melted add the flour, whisk to combine - this is your roux. Whisking constantly, slowly pour the cold milk into the flour mixture, adding a little at a time, in order to get a smooth sauce. Once all the milk has been added, bubble the sauce away for 5 minutes until thickened.

Step 5

Grate in all the cheddar and half the gruyere cheese. Once the cheese has melted take the sauce off the heat, add the dijon mustard and season with salt and pepper.

Step 6

Add the cooked macaroni and caramelised onions into the cheese sauce, reserving a tablespoon of the onions. Mix well to combine, and then top with the remaining onions, a grating of gruyère and your breadcrumbs. Add a handful more thyme leaves.

Step 7

Place under the grill until bubbling and golden brown. Remove from the oven and tuck in. Enjoy!