Put in a preheated oven at 200°C/400°F/Gas 6 for 10 minutes, until the cheese has melted.
Top with mashed avocado, creme fraiche and jalapenoes.
If you are using store bought tortilla chips, make sure they are really thick ones. The black bean topping is pretty heavy, and the tortilla chips need to be able to hold the weight of them when you scoop everything up.
If you want to make the clean up a lot easier, then line your baking paper with foil or baking paper first. You don't have to, but it will make things a lot easier for you.
Don't use a bag of ready grated cheese. Although this is a time saving option, store bought grated cheese tends to have a starchy coating on it which prevents the cheese from melting properly, and nachos need to be super melty.
To make the black bean stew topping more like a refried bean mixture, you could blend it a little until it is the desired consistency.
Got some black bean stew left over? Put it in a bowl to serve with everything else, and dip the nachos in it. You won't regret it.