The company is testing the concept at a renovated restaurant in Laguna Niguel, Calif., and at outlets in Illinois, the Orange County, Calif., Register reported Saturday.
The patties are the same as the one used for the familiar Quarter Pounder, but many options are new. Customers order from menus on iPads and the toppings include grilled mushrooms, smoked bacon, garlic sauce and guacamole, the newspaper said.
"With these tests, we will have an opportunity to hear directly from our customers in real-time on what they expect from McDonald's in terms of the overall restaurant experience and their ability to further customized their menu choices," the company said in a statement.
The changes being tested, the Register said, include the option to have a hamburger "chargrilled-to-order."
One industry consultant, Dennis Lombardi at WD Partners in Ohio, said McDonald's was reacting to an assault on its market share from casual restaurants that serve slightly upscale fare.
"When you look at the quick-service restaurant industry, they have been striving to close the gap with the fast-casual players," Lombardi said.