Preheat the oven to 425 degrees F. Line a baking sheet with parchment paper.
In a food processor, pulse the spinach and shredded mozzarella until finely chopped. Add the egg and pulse until fully combined.
Transfer the spinach mixture to the prepared baking sheet. Using a spatula, spread into a 10-inch circle, a little less than ⅛-inch thick. Be sure to spread evenly—if the center is too thick, it won’t cook through. Bake until the crust is set and puffs in center, about 17 minutes.
While the crust bakes, in a small bowl, combine the crushed tomatoes, garlic, and a pinch each of oregano and crushed red pepper. Season with salt.
Remove the baking sheet from the oven and increase the heat to 500 degrees F. Then, spread the tomato sauce over the crust, leaving a ½-inch border. Evenly top with sliced mozzarella.
Once the oven has reached 500 degrees F, return the baking sheet to the oven. Bake the pizza until the cheese is melted and bubbly, about 10 minutes.
Top with basil, slice, and serve.
Photography and styling by Jenny Huang