Preheat your oven to 375 degrees Fahrenheit
In a blender, combine tofu, vegan egg replacer, soy milk, nutritional yeast, and all spices and blend until smooth. Mixture should be the consistency of very thick pancake batter.
Add oil to a skillet over medium-high heat. Once the oil begins to ripple, add onions and sautée until fragrant. Add mushrooms, ½ cup tomatoes, and spinach and cover with a lid. Reduce heat to medium-low and heat until spinach is just wilted.
Pour blended quiche filling into a large mixing bowl and gently fold in ½ cup of shredded cheese and sautéed vegetables until well combined.
Pour filling into pie crust. Sprinkle with remaining cheese and tomatoes. Bake for approximately 40 minutes until crust is golden brown and filling is firm to the touch.
Allow to cool for around 15-20 minutes before serving. Enjoy!