Steps
- Peel 700g of starchy potatoes and cut into ¾in / 2cm rounds. Cover with cold salted water in a saucepan, bring to a boil, and cook for 15-20 minutes, until very tender.
- Drain, reserving the water. Steam-dry for 5 minutes, then press through a fine sieve into the saucepan.
- Tear 3 whole-milk mozzarella balls. Microwave 250ml of warm heavy cream, 50g of melted salted butter, and one-third of the mozzarella on high for 45-60 seconds, until melted.
- Mix into the potatoes with the remaining mozzarella, 70g of grated cheddar, 70g of grated Comté, and 70g of grated Taleggio.
- Stir over low heat until the cheeses melt into a smooth, stretchy mash, loosening with a little reserved cooking water if needed. Season with salt and pepper.