The 5-year-old's culinary creation is now on the menu of The Bay Cafe, in Macandrew Bay, after he beat 29 others in a pizza design competition.
Cafe owner Chris Smith said he approached Macandrew Bay School about the competition and pupils were asked to dream up a pizza topping using ingredients of their choice and colour in a picture.
"The school loved it," he said.
While there were a few "curly" toppings, three pizzas were chosen to go on the cafe's menu for four weeks.
William's dessert pizza, a chicken, bacon, apricot and cream cheese pizza and a caramelised onion, steak, broccoli and cashew pizza went head-to-head for the chance to go on the menu permanently.
The competition finished last Saturday night and it was only a "last-minute phone order which tipped it in William's favour", Mr Smith said.
"It was very close. It was amazing how everyone got behind it."
William said his "choconana pizza" was easy to create "because I like pizza".
His class will get a pizza lunch next term and his family will get two free pizzas a week for one month from the cafe.
Though unsure whether this pegged William for a career in the food industry, his father, Richard, said William's mother was "a bit of a foodie" and he enjoyed pulling a chair up to the kitchen bench to help with food preparation.
