Sift the flour into a large mixing bowl. Stir in the yeast, caster sugar and salt until evenly mixed.
Add the warm water and mix until the dough starts to come together. Press the dough together into a ball, then turn out onto a lightly floured surface.
Knead the dough for 10 minutes until smooth and elastic. Spray the mixing bowl with a little low-calorie cooking spray and use it to grease the bowl. Place the dough, seam-side down in the greased bowl and cover with a plate. Put it in a warm place to prove for 1 hour, until the dough has at least doubled in size and feels puffy when pressed.
In a small bowl, combine the tomato purée, water, sweetener, mixed herbs, garlic and pepper and mix until smooth. Leave to one side. Spray the cake tin with low-calorie cooking spray and grease well.
Turn the dough out onto the surface and lightly knead just four or five times. Form into a smooth ball placing seam-side down on the surface.
Divide the ball of dough into 16 equal-sized pieces. Take the first piece of dough, place it on the work surface and flatten it into a round with your hands.
Spread a little of the tomato purée mixture into the centre of the dough, add one of the cubes of mozzarella and some of the pepperoni. Fold the edges in to encase the filling inside the dough ball pinching firmly to seal. Gently roll in your hands to make a smooth ball. Repeat this process until you have made 16 dough balls.
Grease a 20cm round cake tin with a little reduced-fat spread. Place all the dough balls seam-side down in the prepared tin, setting them closely together. Cover with a plate and put them in a warm place to prove for a further 30 minutes, until they are puffy when pressed, have increased in size and are joining together.
Remove the plate and place the tin into the air fryer and cook at 180°C for 8 minutes until golden brown and joined together. Depending on the size of your air fryer you may need to use two smaller tins or cook in batches.
In a bowl, add the spread and garlic and mix until smooth. Once cooked, brush the dough balls with the garlic ‘butter’, remove from the tin and place onto a serving plate.