Method
Pre-fire your wood oven. It should be around 350°C when you start to cook.
Put the onions into an ovenproof heavy-based frying pan, toss them with a little olive oil, sea salt and pepper and transfer the pan to a medium-hot area of the wood oven. Cook for 20–30 minutes until they are soft and have taken on a little colour, stirring them regularly and ensuring they don’t burn.
Meanwhile, take the kale off its stalks and tear it into little pieces. Once the onions are soft, add the kale to the pan and return to the oven. The heat of the oven should soften the kale very quickly. Set aside while you prepare the pizza bases.
Sprinkle your work surface with a little semolina or polenta. Place one ball of dough on the surface and stretch it out by hand to a large round, 25–30cm in diameter, leaving a little ridge around the edge. Repeat with the second piece of dough.
Dust a pizza peel with more polenta or semolina (if you don’t have a peel, an upturned baking tray is a good substitute). Transfer one pizza base to it.
Top the pizza with half the onion and kale mix, anchovies, mozzarella and grated Cheddar. Finish with a drizzle of olive oil. Gently slide the pizza onto the base of the oven. Depending on the heat of the oven, it will take between 3 and 5 minutes until the base is cooked, the cheese is bubbling away and the kale is nice and crispy. Slide the pizza out of the oven then assemble and bake the second pizza.