Cover potato and sweet potato with cold water in a medium saucepan. Season with salt. Bring to the boil for 5 - 10 minutes or until tender. Drain and set aside

Heat oil in a 20cm shallow pan. Fry onion until soft. Add mushrooms; continue stir frying for 2 minutes

Add cooked potatoes; stir fry for a further 2 minutes. Set half of the vegetable mix aside

Lightly beat 4 eggs. Pour over vegetables, add 50g prosciutto. Cook on a medium heat until nearly cooked through

Drizzle approx. 50ml Birch & Waite Hollandaise over the top of the frittata and finish under a griller until the top is just cooked

Repeat to make the second frittata

Add extra Birch & Waite Hollandaise just prior to serving