McDonald's is rebuilding its U.S. kitchens to make way for fresh and customizable menu options.

The fast food giant is building new "prep tables" to make it easier for workers to chop fresh produce and make custom burger toppings, McDonald's CEO Don Thompson said on an earnings conference call today.

The tables will be in many restaurant kitchens by the end of the year, Thompson said.

In addition to paving the way for fresh ingredients, the new kitchen system will give McDonald's "the flexibility to have new toppings and customize food products," he said.

McDonald's faces mounting competition from fast-casual chains like Chipotle, Panera Bread, and Five Guys.

These chains appeal to consumers because they are perceived as being fresher and higher-quality than other fast food chains.

Chipotle workers, for example, prepare food in plain view of customers.

In the coming years, McDonald's is expected to focus on offering more fresh fruits and vegetables, as well as sustainable fish and cage-free eggs.

McDonald's is also testing a program in California that lets customers customize their burgers.