The owners of BRGRBelly — once known as Leadbelly — plan to open a third restaurant this fall, this one focusing on Italian Beef. View Full Caption Flickr/Arnold Gatilano; BeefBelly

CHICAGO — The restaurateurs behind BRGRBelly, 5739 W. Irving Park Road, and BeefBelly, 4800 N. Central Ave., will donate a chunk of their earnings Wednesday evening to ensure that Luther North College Prep has enough money to hold prom before it closes for good in June.

Owners Steve and Nicole O'Brien will set aside 20 percent of proceeds raked in between 5-9 p.m. at both restaurants — plus their sweet shop, Molly and Myles Ice Cream, around the corner from BeefBelly at 4802 N. Central Ave. — for the Portage Park school, they said.

The principal of Luther North, 5700 W. Berteau Ave., announced in February that declining enrollment and financial struggles led the school's directors to end its 108-year run this summer.

Principal Wayne Wenzel then told parents and alumni that the school was staring down a $225,000 budget shortfall this year, potentially forcing the school to end classes early or cancel senior prom if the gap isn't closed in time.

The fundraiser is a "passionate issue" for Nicole O'Brien, who is a Luther North alumna, according to her husband.

"It really hit her heart when she heard it was closing, and when we heard they were looking for funding, we wanted to step up," Steve O'Brien said earlier this week. "We've catered and supported Luther North events in the past, so we're glad we have the chance to do one last thing for them."

Weather permitting, the event will also be an opportunity for the owners to tout their new open-air windows at BRGRBelly, which give the restaurant an "al fresco" feel, O'Brien said.