Add the cauliflower florets to a food processor and pulse until they resemble fine rice. Transfer the riced cauliflower to a large skillet and cook over medium heat for 6–8 minutes, stirring frequently, until softened and any excess moisture has cooked off. Remove from heat and let cool slightly.

Transfer the cooked cauliflower to a clean kitchen towel and squeeze out as much liquid as possible. This step is key for a firm crust.

In a mixing bowl, combine the drained cauliflower, egg, salt, oregano, Parmesan cheese, and minced garlic. Stir until fully combined.

Press the mixture onto the prepared baking sheet in a thin, even circle about ¼-inch thick. Bake for 20–22 minutes, or until the crust is golden and set.

Remove from the oven and spread marinara sauce over the crust. Sprinkle with mozzarella and arrange pepperoni on top.

Return to the oven for 7–10 minutes, or until the cheese is melted and bubbly. Let cool slightly before slicing and serving.