Preheat the oven to 200°C (400°F) and line a large baking sheet with parchment paper.
In a large mixing bowl, combine the ground chicken, 2 cups shredded cheddar cheese, Italian seasoning, and olive oil until evenly mixed.
Form the mixture into a tight ball, place it on the prepared sheet, and press it into a large, even pizza-shaped crust about 1/2 inch thick.
If you prefer a crisper crust, prebake the crust for 5 minutes until it firms slightly.
Remove the crust from the oven and spread 1 cup tomato sauce evenly over it.
Top with sliced mushrooms, chopped bell pepper, and 1 cup shredded mozzarella cheese.
Bake the assembled pizza for 8–10 minutes, or until the cheese has melted and toppings are heated through.
Remove from the oven, let rest for a minute, slice, and serve.
