Combine the green split peas and water over medium-high heat. Bring to a boil, cover, and reduce heat to medium-low. Simmer for 35 to 45 minutes or until the split peas are very tender and mushy, adding more water to keep the peas submerged, if needed. Strain off excess water.
Meanwhile, steam the baby spinach in a steamer or steamer basket for 15 minutes or until tender.
While the spinach is steaming, whisk together the chia seeds and filtered water in a small bowl. Let stand for 10 minutes to create a chia "egg".
Preheat oven to 400F. Line a large round pizza pan with parchment paper.
Once the spinach is cool enough to handle, press and squeeze it between your hands to release as much of the excess water as possible. By the time you’re done squeezing, you should have just under a half cup of steamed spinach.
Add the spinach and cooked split peas to a food processor, and process for 1 minute or until it’s almost completely smooth. Transfer to a large mixing bowl along with the chia egg, oat flour, almond milk, almond flour, olive oil, apple cider vinegar, garlic powder, basil, oregano, sea salt, and red pepper flakes (if using). Use a large wooden spoon to stir together until combined. It will be a wetter, spreadable, gooey dough.
Scoop the potato dough onto the parchment paper and use a clean spatula to spread it into a large 10x12-inch oval on the pizza pan. It should be not more than 1/3-inch-thick. This process takes a few minutes, so be patient as you're smoothing out the crust. If the crust is sticking, lightly grease the spatula with olive oil.
Bake for 20 to 25 minutes or until the crust is set, the top is crackled, and the edges and bottom are just beginning to turn light golden.
Remove the crust from the oven and let cool slightly before adding toppings.
Add any toppings your heart desires. Enjoy as is or bake another 5 to 10 minutes or until toppings reach desired doneness.