Possibly Pizza to Go by Tom Holt.
It starts at the feeding of the five thousand where:
"I see," said Jesus Christ. "You forgot to tell them to bring sandwiches."
"It's Peter's fault," said Barnabas pre-emptively. "I asked him what we were going to do about catering, and he said no worries, he had a mate who could give us a really special price - "
"We're going to get lynched," John groaned. "There'll be little bits of us scattered about all the way to Caesarea."
"Don't be silly," said the Messiah. "Leave this to me. Honestly, if it wasn't for me, I don't know what you'd do." From his sleeve he took a mobile phone and a small piece of card, on which was written:
PIZZA TO GO
The lady is Bianca di Fiesole who is rescued from Renaissance Italy by the time travelling pizza man (actually a woman) when her entire family is poisened. The story ends:
Because this is Bianca's kitchen, possibly the most extraordinary place in spacetime. From this small prefabricated industrial unit - well, indeed, skip all that. We may have been here before.
There's Rocco and Tony, who make the bases; Freddy and Mike, who do the toppings; Carlo, who minds the ovens; Rosa and Vito and Zelda, who chop the vegetables and deal with the side-orders; Frankie, Ennio and, of course, young Gino, who do the deliveries; and there's Momma Bianca, who takes the orders, writes out the tickets and does everything.
Occasionally her eldest daughter Zelda suggests it might help if she were to take a turn answering the phone occasionally, so as to give Momma a break at her age. And Bianca says yeah, that'd be good. As soon as the rush is over.
When people ask her how she copes, Momma Bianca grins. "It's a family business," she says.