Whisk flour and salt together in a large bowl.

Add water and milk gradually, whisking until the batter is smooth and thin, close to heavy cream in thickness.

Cover and let the batter rest at room temperature for 30 minutes. Skip this and the panigacci turn gummy in the center even after they look browned outside.

Heat a cast iron skillet or crepe pan over medium-high heat until a drop of water sizzles and evaporates within a second.

Wipe the pan with a paper towel dipped in olive oil, just enough to coat the surface.

Pour a scant 1/4 cup of batter into the pan and tilt quickly to spread it into a thin round about 10 cm across.

Cook for 60 to 90 seconds until bubbles form and the edges lift and turn golden.

Flip and cook the second side for 45 to 60 seconds until lightly spotted brown.

Stack cooked rounds inside a folded kitchen towel to keep them warm and soft. Regrease the pan lightly every 3 to 4 rounds and repeat with the remaining batter.

While the panigacci are still warm, spread each round with stracchino, add a slice of prosciutto or a spoon of pesto.

Fold each round in half or into quarters and serve immediately.