Make mashed potato: Peel potato, cut into 2.5cm / 1" chunks. Boil until fully tender (around 10 – 15 mins; check centre with skewer). Drain and mash very well with a potato ricer or masher until smooth and lump-free. Set aside to cool, and measure out required quantity.
Mix Dry: Place flour, salt, sugar and yeast in a large bowl and mix well with a firm rubber spatula.
Add Wet: Make a well in the centre, then add olive oil and warm water. Mix with spatula until you can no longer see flour. Dough should be sticky – too sticky to knead by hand.
Add Potato: Add mashed potato. Using a folding motion, start mixing it through using the spatula. Then start smearing it along the walls of the bowl. Once potato is evenly incorporated, shape roughly into a ball in the bowl.
Rise 1: Cover bowl with cling wrap, then put in a warm place (25°C/77°F) for 30 minutes until it increases in volume by 50% or up to double in size.
Fold dough: Get another large bowl, drizzle with 2 teaspoons of olive oil then use your hands to smear it around the bowl. Scrape dough in, then fold the edges of the dough into the centre six times. Shape into ball, cover with cling wrap.
Rise 2: Put the bowl in a warm place (25°C/77°F) for 30 minutes until it increases in volume by 50% or up to double in size.
Prepare pan (see Note 7 for pan types info): Meanwhile, prepare the pan. Use a 26.5 x 20 x 5 cm / 10.5 x 8 x 2” metal non-stick pan, or a 9”/23cm round cake pan, preferably not springform. Pour in 2 tablespoons of olive oil, then smear it all across the base and along the walls.
Preheat oven: Preheat oven to 220°C / 430°F (200°C fan), and set a rack on middle shelf. Allow enough time to ensure oven has been preheated for at least 15 mins for best results.
Put dough in pan: Scrape dough into prepared pan. Stretch and pull to fill the base as best you can (itʼs an elastic dough so a bit stubborn!), and get the surface roughly level. Itʼs ok if itʼs bumpy, it will smooth out later.
Rise 3: Cover pan with cling wrap, then put in a warm place for 40 minutes until the dough expands and fills the pan, and the heigh rises by around 25 – 30%.