In a deep baking dish, arrange 1 bag of corn chips so they cover the base, then set aside.
Heat olive oil in a medium-sized pot and gently fry onions until they start to become clear, add garlic and tomatoes and fry for a couple of minutes, until tomatoes start to soften.
Add the tin of refried beans and heat through then add a small handful of the cheese, stirring until melted. If needed, thin mixture with a little water to give it a pouring consistency. Add salt and pepper to taste.
Take off heat and pour half of the mixture over the 1st layer of nachos then sprinkle with 1/4 of the cheese.
Arrange the 2nd bag of nachos over the first layer then pour over the remaining refried bean mixture, sprinkle over the remaining cheese and place the sliced jalapenos over the top.
Place under a preheated grill on medium to high heat and grill for about 5 - 8 minutes or until cheese has melted and just started to brown around the edges. Be careful not to put dish too close to the griller as any exposed chips may burn.