Bring a medium pot of water to boil over high heat. Add the russet potato and cook until fully tender.

Remove potato from water, let cool, then pass through a potato ricer, or mash by hand with a fork in a medium bowl. Add butter and double cream (or milk, if using).

Fold in the ricotta cheese until fully incorporated. The potato mixture should have a creamy, slightly whipped consistency. Add additional cheese and/or milk if needed.

Season generously with salt and pepper. Let cool to room temperature before topping the pizza.

To make the caramelised onions, heat a medium-sized heavy-bottom pan over medium heat. Add 1 tablespoon of extra-virgin olive oil followed by the sliced onions.

Stirring often, sweat the onions briefly to soften, around 10 to 15 minutes. Continue cooking over very low heat until lightly golden brown, about 45 minutes.

Season with salt and let the onions cool to room temperature before topping the pizza.

Next, place the diced fingerling potatoes and rosemary sprigs in a medium bowl. Toss well with a generous amount of extra-virgin olive oil and season with salt.

Fire up your Ooni oven, then place the cast iron skillet inside, close to the opening. Let the pan preheat with the oven for about 3 minutes.

Add the potatoes to the hot pan and roast until softened and gently browned about 5 to 7 minutes. Turn the pan as needed for an even cook and scrape up any crispy bits.

Once the potatoes have cooked, remove the pan from the heat, adjust the seasoning as needed and let cool.

Alternatively, you can heat your home oven to 200°C with the fan on, or 230°C with it off. Roast the potatoes until softened and gently browned, about 10 to 15 minutes. Adjust seasoning as needed and let cool briefly before using it to top your pizza.

Tip: If you use your home oven to roast the potatoes, be sure to preheat your Ooni oven so it will be hot enough for the bake.

To make the pizza, increase the temperature of the oven, aiming for 425°C to 450°C in the centre of the baking stone. Use an infrared thermometer to quickly and accurately check the temperature.

To stretch your dough ball, use your finger pads to push the air from the centre of the dough ball out to the edge, still preserving a crust. Stretch the dough out to form a 14-inch (36cm) base, being careful not to make it too thin (with heavier toppings, thicker is better), then lay the dough over your lightly-floured pizza peel.

Top with ½ tablespoon scoops of ricotta mashed potatoes, we ended up only using half since more was too much, spaced about one inch apart and leaving room for the crust.

Sprinkle with shredded sharp cheddar cheese, followed by fresh mozzarella and caramelised onions. Top with roasted potatoes and salt and pepper to taste.

Slide the pizza off the peel and into the oven. Cook for 3 to 5 minutes, turning the pizza and checking the bottom regularly to ensure an even bake. Adjust the flame as needed to ensure a crisp bottom and browned crust.

Remove the pizza from the oven and let it rest briefly on a wire rack, for about 1 minute.

Top with minced fresh chives, slice and serve immediately.