To make the dough, mix together all the ingredients with enough warm water to make a nice soft dough. Knead the dough for 5 minutes until soft and smooth. Place in a bowl, drizzle the top with a little more olive oil. Cover and eave to rise in a warm place for at least 40 minutes, or double in size. When ready, knock back the dough and divide into 2 pieces. Use a little semolina to open out the dough into 2 oval shapes. Place onto baking sheets sprinkled with more semolina. In a small saucepan, melt together the garlic butter and all the dried herbs. Brush evenly over the pizza dough. Next, Place the defrosted spinach and mozzarella into a colander or sieve and squeeze out any excess water. Arrange over the top of the foccacia, top with the sliced mushrooms and finally sprinkle over the grated Parmesan cheese. Allow to rise for another 30 minutes, then bake in a hot oven at 220`c for 20-25 minutes.