The humble onion is a vital ingredient in a classic mirepoix base for stocks, sauces and soups, or can be a sharp raw crunch when added to a salsa. Though pungent, they are versatile and boy, do cheese and onion make a great partnership.

A close friend’s husband took up cooking while raising a young family, and his success in creating slow cooked meat dishes with gutsy flavours was an inspiration to all the other new dads at the time.

During his tenure as chief cook, he also made this delightful onion tart, an elegant vegetarian starter, and here is how I remember it. To make pastry, rub the butter into the flour until it resembles breadcrumbs. Mix in the egg, to form a dough. Wrap and leave it to rest in the fridge for 20 minutes.

Preheat your oven to 180 degrees Celsius. Bake the pastry blind by rolling it out to fit a 20cm loose-bottomed tart tin, lined with parchment paper. Fill the tart tin with baking beans, then bake for 20-25 minutes.

In a heavy-based frying pan, gently fry the onions in butter on a low and slow heat, being careful not to burn them. After 30 minutes, the onions should have caramelised and be golden brown in colour. Increase the heat slightly to achieve this if you have to. Stir in the herbs and season. Set aside to cool.

Lightly whisk the three eggs, add the milk and cream. Season with salt and pepper and a pinch of nutmeg.

Spread the onions over the prebaked pastry base. Slowly pour the egg mixture over the onions, making sure that the ingredients are spread evenly across the tart. Lay the Cashel Blue cheese and walnuts over the top of the filling. Bake for 35-40 minutes, until the tart is firm and golden brown.

Serve warm with a salad of mixed leaves.