Pre-heat the oven to 180C. Grease a springform pan with oil and set aside.
In a large skillet over medium-high heat, add the onion, garlic, olive oil and dried thyme. Cook, stirring often, for 5-8 minutes, or until the onion has softened and browned just a bit.
Add the broccoli florets to the bowl of a food processor and pulse 3 to 4 times, or until the florets are just broken down (you don’t want to fully blitz the broccoli).
Add the broccoli to the skillet with the onion and garlic mixture and cook for 3 minutes, stirring often. Next, add the spinach and 1teaspoon of salt and cook until the spinach is wilted – no longer than 2minutes.
Add the tofu to the bowl of the food processor, along with 1teaspoon of salt, the turmeric, brewer’s yeast (if using) and lemon zest, and blitz until smooth.
Add the spinach and broccoli mixture to a large bowl, followed by the puréed tofu and the cooked peas. Gently mix the ingredients until everything is well incorporated. Season with freshly ground black pepper and an extra pinch of salt, if necessary.
Add the frittata mixture to the prepared springform pan. Smooth the top with the back of a spoon and bake in the oven for 40-45 minutes or until golden brown. Let it cool in the pan before unmolding and serving.