Dissolve yeast in 500 ml of very cold water. Mix flour, salt and yeast water with a wooden spoon to a soft dough. Seal the dough airtight in a bowl at least twice the size. Leave to rise at room temperature for approx. 4 hours, or chill for at least 12 hours
Cut baking paper into 12 pieces of approx. 20 x 20 cm. Place a piece of baking paper in each well of a muffin tray (12 wells). Press the centre of the paper onto the bottom of the muffin pan and fold the edges all around so that the troughs are laid out
Grate the gouda finely. Pluck the mozzarella finely. Cut tomatoes into large cubes. Knead cheese and tomatoes into the dough. Form into 12 balls on a floured work surface and place in a muffin tray lined with baking paper. Bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 40 minutes
waiting time at least 4 hours