Preheat your oven to 425°F.
In a food processor, combine the cauliflower and egg white. Blend until the mixture turns into a rice-like texture.
Transfer the cauliflower mixture to a bowl and microwave for 4-5 minutes, then let it cool. Once cooled, squeeze out excess moisture using a clean towel.
Press the cauliflower mixture onto a parchment-lined baking sheet forming a thin, even circular crust. Bake in the oven for about 12-15 minutes or until the edges become light golden.
While the crust bakes, season the chicken breast with your favorite spices and grill or pan-sear until fully cooked. Once cooked, slice into bite sized pieces.
Remove the crust from the oven and spread a thin layer of BBQ sauce evenly over it.
Layer the cooked chicken slices, red onion, and bell pepper on top of the sauce.
Sprinkle the low-fat mozzarella cheese evenly over the toppings.
Return the pizza to the oven for an additional 5-7 minutes, or until the cheese is melted and bubbly.
Remove from the oven, let cool for a minute, slice, and serve immediately.