Heat the oil in a large pan and sauté the onion for 3 minutes until starting to soften. Add the garlic and the spices and fry for a further minute, stirring constantly.
Stir in the beans, jalapeños, sweetcorn and spring onions and cook gently for 5 minutes to heat through.
For the cheese sauce, melt the butter in a pan then beat in the flour and cook for 30 seconds, stirring. Gradually whisk in the milk, stirring all the time until the sauce thickens. Add 30g of the grated cheese and season.
To assemble the lasagne, place a third of the bean mixture in the base of the dish, followed by a layer of tortillas, cut to fit the tin, top with a thin layer of cheese sauce then repeat the layers, finishing with a layer of cheese sauce.
. Sprinkle the remaining cheese over the top and bake in the oven for 25-30 minutes or until golden brown and core temperature is reached.