My grandmother's pizza what's the secret?

The grandchildren wanted to surprise their grandmother with a visit. Grandma was very happy, but they didn't like old-fashioned foods. So, Grandma asked them to help her prepare the food, without revealing what she intended to cook. In the garden, Grandma gave instructions for picking vegetables, while Nadeem kept taking pictures of them all. At lunchtime, the grandchildren returned from playing, and a delicious aroma wafted from Grandma's kitchen – a smell they knew well, the smell of pizza, and it was the best pizza they had ever tasted. They wondered about the secret to Grandma's delicious pizza, and when they returned home, they sent the photos to relatives under the title "Grandma's Pizza... What's the Secret?"