Add the flour to a large mixing bowl. Then add the yeast, sugar, and salt, and mix.
Pour in the warm water and mix until the dough starts to come together. The dough should appear quite shaggy and loose.
Press the dough together into a rough 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 place the dough in the bowl. Cover and leave to prove in a warm place for 1 hour. The dough should have at least doubled in size, and feel puffy when pressed.
Turn the dough out onto the surface and lightly knead for a couple of minutes. Then form into a smooth ball, and divide into 16.
Take the first piece of dough and flatten it into a round with your hands. Place a cube of mozzarella in the centre, and form the dough around to seal into a ball shape. Repeat this process until you have made 16 dough balls.
Leaving a few millimetres between each ball, place the dough balls seam-side down onto a lined baking tray in the following formation: 1 ball on row one, 2 balls on row two, 3 on row three, 4 on row four, 5 on row five, and 1 on row six. Cover the tray with cling film, and leave 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.
When the dough balls are nearly done proving, preheat the oven to 200ºC.
Once the dough balls have proved, add the dried cranberries and half the rosemary sprigs randomly between the dough balls. Place the tray into the oven for 10-12 minutes, until golden and joined together. The dough balls should sound hollow when tapped on the bottom.
While the dough balls are cooking, prep the "butter". Finely chop the remaining rosemary and place into a bowl with the reduced fat spread and garlic. Stir well.
When the dough balls are cooked, microwave the "butter" for about 20 seconds, until just melted. Brush over the surface of the dough balls. We added a star shape made from Cheddar cheese to the top of our dough ball tree, but this is optional (and will add 2 calories per portion).