Kevin Newell, a McDonald’s executive, said the offering is attracting a different type of customer and more of a dinner-time crowd. The purpose of the expanded test is to get more data, he said.

Last year, the world’s biggest burger chain began testing a ‘‘build-your-own burger’’ concept in California. A restaurant in Laguna Niguel offers tablets on which people can specify the bun, patty, cheese, and toppings.

‘‘It’ll be more than five, less than a hundred,’’ he said when asked how many restaurants would be testing the menu — all in Southern California.


The chain is also rolling out new prep tables in kitchens at more than 14,000 US restaurants — built to accommodate many more toppings and dressings, suggesting the company plans to expand its lineup of ingredients.

McDonald’s has already made adjustments in the test, too, such as cooking its Quarter Pounders on a flat grill instead of char-grilling them.

‘‘We’ve got to figure out, can we do it operationally?’’ Newell noted.