Mix together the water, sugar, salt and yeast in a large bowl and wait until it starts to foam a little then stir in the flour. Knead into a soft dough and then place in an oiled bowl. What you do now depends on how much time you have. For this pizza we left the dough in the fridge for the whole afternoon (about 6 hours) to rise and it turned out really well but if you don't have that much time you could leave it somewhere warm for 1-2 hours.
While the dough is proving preheat the oven to 200°C. Make the pesto by grinding the rocket, olive oil, pine nuts and garlic in a pestle and mortar or a mini food processor. Once the dough has doubled in size remove it from the bowl and knead for a minute. Halve the dough and roll out each piece to a big enough size to fit the skillet then gently lift one into the skillet making sure to leave a slightly thicker crust around the edge. Spread over half the pesto and sprinkle over half the chicken and mozzarella.
Place the skillet on the hob over a high heat for about 5 minutes to allow the skillet to get really hot. Place the pizza in the oven for about 18-20 minutes. Remove and repeat with the second pizza. Serve topped with a handful of fresh rocket.