Peel and dice sweet potato, boil until tender then mash and leave to cool
While the sweet potato is cooking, mix 1Tbs ground flaxseed with 3Tbs water to make a flaxseed egg. Leave for 10 minutes to thicken
Mix the mashed sweet potato with buckwheat flour, flaxseed egg, nutritional yeast and salt. Knead well and form a ball of dough
Line a baking tray with parchment paper and press dough until flat (you may want to do this with wet hands, or alternatively you can lay a sheet of paper over the dough and roll with a rolling pin). Form into a rectangle or circle.
Put in the oven and cook for around 20 minutes until crisp around the edges
While the base is cooking, prepare toppings. Put vegetables and herbs into a bowl with olive oil and mix thoroughly
Take base out of the oven once cooked and spread with tomato paste then top with tomato slices and spinach. Pile vegetables on top and put back in the oven for around 15 minutes until cooked through.
Take pizza out of the oven once cooked and add spoonfuls of cashew ricotta, serve and eat!