The chain has announced a contest that will award $1 million to the customer who develops the next successful iteration of the Whopper. Ideas will be gathered through March 17 at the chain’s website.

Once the deadline passes, Burger King officials will then evaluate the entries for “feasibility, popularity, and innovation.” Three finalists will then be invited to the company’s headquarters to fine-tune their ideas.

In November, all three of the finalist burgers will be made available for a limited time. Guests will vote for their favorite, with the winner getting the grand prize—and the other finalists getting smaller cash rewards.

So, how far can you let your burger imagination run? Pretty far, actually. Burger King says you can’t add toppings that include peanuts or shellfish, including shrimp, crab, lobster, or crawdads. And, specifically, the rules state “Toppings must be edible food items. (duh!)” Entrants will suggest between three and eight toppings.

The contest site asks you to list your ingredients, then will present an AI-generated image of what your burger might look like.

Don’t think about suggesting a different sort of bun or burger (other than the standard beef or Impossible options). Those base elements won’t change, the company says. And, sure, you could suggest adding truffles or edible gold leaf, but that’s probably not the path to victory.

“Keep in mind Toppings will be subject to a feasibility score that considers the practicality of using the Topping on a hamburger prepared at a Burger King restaurant,” the rules state. “So, consider the availability, the cost of the Topping, and whether it’s something our Burger King restaurants can easily store, prepare, and use on a Whopper sandwich.”