Preheat oven to 400°. Line a baking sheet with parchment paper and olive oil.
To make pizza crust, coat cauliflower florets in olive oil, oregano and salt. Roast for 15 minutes, stir, and cook for an additional 10 minutes, until soft and just beginning to brown. Set aside to cool.
Combine chia seeds with ¼ cup of water. Allow seeds to jell for 15 minutes, creating a “chia egg.”
In a food processor, pulse roasted cauliflower, chia egg, chickpea flour and ¼ cup water.
Spread “dough” on prepared baking sheet. Bake 25–30 minutes, until crust is golden.
To make sauce, in food processor combine sun-dried tomatoes, roasted peppers, Parmesan cheese, garlic, basil, oregano and olive oil. Process until completely smooth. Season with salt and pepper, to taste.
Spread sauce over crust. Sprinkle with Parmesan cheese; return to oven for 7 minutes, until cheese melts.
Remove from oven and top with arugula, walnuts and olives.