Preheat your oven to 425°F (220°C).
Steam or microwave the cauliflower until tender, then process in a food processor until rice-like consistency is achieved.
Place the cauliflower in a clean towel and squeeze out excess moisture.
Mix the cauliflower, egg, garlic powder, salt, pepper, and a splash of olive oil until well combined to form a dough.
Press the cauliflower mixture onto a parchment-lined baking sheet to form a circular crust, about 1/4 inch thick.
Bake the crust in the oven for about 15 minutes until it starts to firm up and turn golden.
Meanwhile, season the chicken breast with salt and pepper. In a skillet, heat the remaining olive oil and cook the chicken for 5-7 minutes per side until fully cooked. Let it cool a bit, then slice thinly.
Remove the crust from the oven. Spread a thin layer of basil pesto evenly over the crust.
Distribute the sliced chicken evenly on top, then sprinkle with shredded mozzarella cheese.
Return the pizza to the oven and bake for an additional 8-10 minutes, or until the cheese is melted and bubbly.
Remove from the oven, let it rest for a couple of minutes, slice, and enjoy your Cauliflower Crust Chicken Pesto Pizza!