Evil under the Tuscan sun / Stephanie Cole.

Enhanced descriptions from Syndetics:

Nell Valenti is at ease when managing a farm to table cooking school in sun-dappled Tuscany, but begins to feel the heat when tasked with catching a killer, in this engaging Italian-set cozy mystery series.

When a wealthy New York philanthropist pays top dollar for a private, four-day ziti workshop, Nell Valenti wants everyone at the Orlandini cooking school focused on the task at hand. But complications abound when Nell's boyfriend Pete Orlandinirushesto Rome for an unexpected business trip, Chef Orlandini is more preoccupied with a potential spot on an American cooking show than preparing for the workshop, and an uninvited woman sneaks into the villa to inspect Pete's olive grove. The last disturbance proves deadly, and when the woman's body is found in the grove, Nell must investigate before her hopes for the workshop, like the olives, are crushed.

Nell now has another item on her checklist--keep the Orlandinis out of trouble and the wealthy ziti-lovers happy while she looks into the stranger's past. When Nell discovers that for one of the Orlandinis, at least, the murder victim was not such a stranger after all, she'll learn that when a detective goes digging in Italy, she'd better be ready for truffle.