Garlic and Spring Onion Butter: Melt 2 tablespoons of the butter in a saucepan. Add the spring onions, thyme and garlic. Simmer for 5-6 minutes over a medium heat, stirring.
Stir in a pinch of salt, pepper, lemon juice and stock powder; heat gently. Remove the saucepan from the stove and immediately stir in the rest of the butter. Set aside.
Rosemary Potatoes: Preheat the oven to 170 degrees C.
Wash, peel and slice the potatoes. Mix the potatoes well with the olive oil, 1 tablespoon rosemary, salt, pepper and half of the oregano until all of the potato slices are covered.
Bake the potato slices in a shallow baking tray in the oven for about 25 minutes turning over now and then. Remove from the oven when they begin to brown. Remove from the baking tray and place on paper towel to absorb excess oil.
Assembly: Prepare the pizza dough and pre-bake briefly in the oven.
Spread the garlic and onion butter over the dough. Sprinkle the grated mozzarella over it and the rest of the rosemary and oregano. Lay the potato slices on top of the pizza and bake at 220 degrees C for about 10 minutes.