Archbishop Vincenzo Paglia flew in from Rome to help plan the September papal visit, pray at the National Shrine of St. John Neumann, and make a decision of pontifical importance:

The official milkshake of Pope Francis' visit.

Would it be crumbled Oreos? Shortbread vanilla? Or a peanut butter, chocolate, banana medley?

Ultimately, Paglia, president of the Pontifical Council on the Family and an important Vatican figure, selected the vanilla and shortbread butter cookie milkshake, in a sweet, strange news conference at a Potbelly sandwich shop in Center City.

That flavor goes by the name #popeinphilly.

It beat out World Meeting Mashup (the Oreo one) and PHL Liberty Bell (the one with peanut butter).

Potbelly will serve the shakes from April 1 to Sept. 30 at its three Philadelphia locations. The store will donate 50 cents from each $3.90 frozen treat to the World Meeting of Families' fund-raising efforts.

The World Meeting has raised $30 million of its $45 million goal for the five-day meeting of Catholic families, which will end with Pope Francis' visit Sept. 25 and 26.

"I'm excited to see good friends and to taste," Paglia said at a table surrounded by students from St. Peter the Apostle School, a caramel colored milkshake in his hand. "You are in a beautiful and splendid city and now I am one of you."

Paglia tasted three milkshakes with Donna Crilley Farrell, executive director of the World Meeting of Families. Then they both deferred to the kids, not knowing the students had been served only one shake, #popeinphilly. That became the de facto winner.

Farrell said similar partnerships were in the pipeline but she declined to specify.

Picking an official cheesesteak or pretzel is unlikely, though. "That's getting into dangerous waters," Farrell said.

Before the Potbelly appearance, Paglia spent the day discussing the Feast of the Family, a Saturday evening program to be held on the Parkway the night before the papal Mass. The event will involve families from five continents, prayer, and music.

"Violence and solitude is globalized; we want to globalize the love of families," Paglia said at the sandwich shop. "On that day, Philadelphia will be the capital of families across the world."

Mia Ortiz, a 13-year-old eighth grader. said her reaction to the event was slight confusion. "I was kind of, like, weirded out by the idea, but, I mean, it benefited us, because we got free milkshakes," she said.

Farrell said she was not concerned that the papal visit would be "overly commercialized."

"People bring a lot of ideas to us and this just seemed like a fun one - I don't think there's worry about that - you watch Pope Francis, people have thrown baseballs to him, you see how he interacts, I think he's fun-loving and he'd support this."

jterruso@phillynews.com

215-854-5506

@juliaterruso