Pre-heat your oven to 200°C / 180°C fan / gas mark 6, then prepare the vegetables. Peel and thinly slice the Jerusalem artichokes (or potatoes) into roughly 5mm rounds. This can be done with the slicing blade in a food processor if you have one or a mandolin. Slice the mushrooms, thinly slice the leeks, peel and crush the garlic, and finely chop the tarragon.

Place the artichoke slices into a roasting tin, drizzle with a little olive oil, sprinkle over the black pepper, then roast for around 20 - 30 minutes until nice and tender, leaving the oven on for later.

Heat a little olive oil with the butter (if using) in a frying pan, then add the garlic and mushrooms and sauté for a few minutes until cooked. Set aside then do the same with the leeks in a little more oil with some black pepper.

Grease well a 20cm square baking tin (or oven proof dish of similar size). Layer up the cooked Jerusalem artichokes, mushrooms and leeks so they are evenly distributed, then scatter over the tarragon and grate the cheese on top. In a jug whisk together the eggs and milk, then carefully pour over the top of the veggies.

Bake at the same temperature for around 20 - 25 minutes until set and golden.  Allow to cool a little and check the temperature before serving.

For toddlers and older children cut the frittata into slices and serve warm with some salad leaves or cooked veggies for a light meal. For younger babies, once completely cooled you can cut the frittata into fingers and serve as a finger food.