Thaw the spinach leaves. Put the spinach, the herbal cream cheese and the pressed garlic in a bowl and stir well together. Season the mixture with salt and pepper. Then add the cornstarch and stir until the mixture thickens a little.
Roll out the pizza dough on a baking sheet with baking paper and divide it into smaller pieces. Place the prepared mass with the crumbled feta cheese on the dough pieces and roll up in a single layer. Brush the dough with the egg yolk diluted with a little water. If necessary, sprinkle some grated mozzarella on top.
Place the spinach rolls in the preheated oven at 200 ° C for about 20 minutes, until the dough is golden brown.