The cost of making a classic Pizza Margherita at home rose at more than twice the pace of overall inflation in Italy last month as olive oil prices soared by close to one-third.

The condiment found in most Italian kitchens saw the biggest increase among the staples tracked by Bloomberg’s Pizza index, which is based on Istat and Economy Ministry data.

The overall cost of making a pizza in July rose 13.5% from a year earlier, compared with a national inflation rate of 5.9%.

A devastating drought in Spain, the world’s biggest producer of olive oil, has caused the spike in prices at a time of dry conditions across the Mediterranean.

The product has been part of Italy’s culinary traditions since before the Romans, who used it for multiple purposes including cosmetics and lamps.

While the cost of electricity needed to cook pizza at home fell, the prices of flour, mozzarella and tomatoes all increased. Here’s the breakdown of the changes:

• Flour consumer prices rose 5.4% Y/y but fell 0.2% M/m
• Mozzarella consumer prices rose 14.2% Y/y and 0.1% M/m
• Tomato consumer prices rose 25.0% Y/y and 2.0% M/m
• Olive oil consumer prices rose 30.6% Y/y and 3.8% M/m
• Electricity consumer prices fell 3.4% Y/y and 4.0% M/m

--With assistance from Mark Evans.