For the sweet potato crust:
Peel sweet potatoes and bake in an oven at 375 degrees until fork tender. Take out of oven and let cool. (If you want to speed up this process you can also chop the sweet potato and steam). In a small bowl combine ground flax and water and mix until consistency resembles an egg.
Preheat oven to 400 degrees.
Once the potatoes have cooled enough to handle, mash in a bowl and add in flax “egg,” flours, olive oil, vinegar, fresh herbs, red pepper flakes, and salt + pepper. Stir until mixture achieves doughy consistency (can add in more flour if necessary!).
Grease a baking sheet with olive oil and using your hands, or a spatula, spread out sweet potato mixture into 6 small circles. Crust should be about ½ inch thick.
Place pizza crust into oven and let bake for about 20-25 minutes. When the crust has browned a bit, take out and let cool.
For the pesto:
Combine the hemp seeds, arugula, salt, spirulina, nutritional yeast, and lemon juice in a food processor. Pulse a few times, and then begin to drizzle the olive oil into the mixture while continuing to pulse until the pesto is smooth. Taste, and adjust if needed with more salt or lemon juice.
For the toppings:
Sauté mushrooms and onion over medium-low heat until slightly browned and cooked through.
Spread pesto over the pizza crust then top with sautéed mushrooms. Place pizza back in the oven for up to 5 minutes until vegetables and crust are warmed through. Place arugula on top of pizzas and stick back in the oven for 30 seconds – 1 minute.
Take out of oven, sprinkle with extra herbs and red pepper flakes, and serve!