Vegetable Cake

1. Preheat oven at 200 degrees. 2. Combine sparkling water, oil, beer and tomato sauce, than add the flour combined with the baking powder and salt and mix well. 3. Put some parchment paper into a big 13x18 inches baking pan and pour the dough mixture. Bake for about half an hour, until a toothpick inserted in the center comes out clean. Let it cool completely and than cut into 3 equal pieces. 4. Meanwhile, prepare the spread. Cook the peas and the carrots until soft. Cook the mushrooms in a frying pan until the whole of the liquid has vapoured. 5. Blend together all vegetables (carrots, cucumbers, peas, spinach) and mushrooms until smoothy. If you prefer, you can leave some pieces of vegetables. Add salt and pepper to taste and let it cool completely. If the mixture is too thick, you can add 1-2 tablespoons mayo or sour cream. 6. Divide the vegetable mixture into 3 equal parts and spread over the cooled tomato sauce biscuits, layering each one on the top of the next, finishing with the last 1/3 of the spread. You can spread some mayo on the top of the cake. 7. Let it stand in the fridge for 2 hours and cut into pieces at your convenience.