Preheat the oven to 450F, or to the temperature listed on the instructions of your store-bought dough or crust.
If using pizza dough, gently knead and roll out the dough into a large circle or rectangle onto a baking sheet that has been slightly oiled (or use a nonstick pan, pizza stone or oiled parchment paper). If it feels sticky, I grab a handful of flour in my hands to rub around the dough as I spread it out. You don't want the shape to be too small, or you'll end up with 4 thick slices. But you don't want it so thin that you create holes. Put some love into it and be patient. ;)
Chop the cauliflower into large pieces, discarding the stem and leaves. Add the pieces to a food processor and pulse until you achieve riced cauliflower. It will resemble the look and shape of breadcrumbs.
Dice the bell pepper and the mushrooms.
Warm 2 tablespoons of olive oil in one frying pan and 1 tablespoon of olive oil in another frying pan. Heat both over medium heat. To the pan with 2 tablespoons, add the cauliflower. Add the peppers and mushrooms to the other pan. Stir to coat the veggies with oil, then add the respective seasonings listed above to each pan. If the cauliflower starts to burn or get dry, add another tablespoon of olive oil.
When the cauliflower is slightly brown and translucent, or if it starts to crisp up, turn the heat to a simmer and stir occasionally until ready to add to the pizza. You'll know when the veggies are done because the mushrooms will be soft and juicy. Turn off the heat. Both pans should only require about 5-10 minutes to cook.
Spread the pizza sauce onto the pizza dough or crust. Make sure to leave the edges bare. Turn off the heat on the cauliflower and add spoonfuls of cauliflower at a time until the pizza is covered to the desired amount. Add the desired amount of sautéed veggies. Place pepperoni slices on top. Add the tomato and some basil leaves, reserving some fresh basil for later.
Brush the crust with olive oil if desired and bake the pizza for 15 minutes. Be sure to read the instructions on your store-bought dough or crust and bake according to the time listed.
The pizza will be done when the crust is golden and the bottom is firm and slightly browned. The center of the pizza should not be soft. I use a spatula to gently lift my pizza so I can check the bottom.
Once the pizza is removed from the oven, use a towel to carefully hold the pan while you slice the pizza. Add fresh basil leaves, torn into smaller pieces.