Bake the fries according to the packet instructions.

Place the chorizo in a large flameproof pan over medium heat on the hob.

Fry for 2-3 minutes, stirring often, until it has released lots of oil.

Add the onions and fry for 5 minutes until soft, stirring often.

Use a slotted spoon to remove the onions and chorizo, placing them in a clean bowl to one side and leaving as much of the oil from the chorizo in the pan as you can.

Take a few pieces of chorizo and dice to small pieces, leave separate from the rest.

Add the butter to the pan and let it melt.

Add the flour.

Whisk until it forms a dough.

Whisk in the milk, bit at a time, until the sauce is smooth.

Remove from the heat.

Stir in the hot sauce.

Add most of the cheese, retaining a handful to top.

Stir until smooth.

Carefully remove the fries from the oven.

Sprinkle over the sliced chorizo and onion.

Drizzle on the cheese sauce.

Sprinkle on the remaining cheese and the smaller bits of chorizo.

Return to the oven for 5-10 minutes until the cheese has melted.