Preheat oven to 450 F.
Place the shredded chicken in a medium sized mixing bowl. Pour the buffalo sauce over top, then stir until chicken is evenly coated.
Place the pizza crust on a baking sheet or pizza stone.
Spread the Sir Kensington's Buffalo Ranch over the surface of the pizza crust, leaving approximately 3/4" border from the edge.
Scatter approximately 2/3 of the buffalo chicken over the pizza, followed by the onion. Sprinkle with both cheeses, then the remainder of the chicken.
Bake in preheated oven on the middle rack for 12-15 minutes, until crust is golden and the cheese is melted and lightly browned.