Preparation Sift flour and salt into bowl. Add egg, then gradually whisk in 1 1/2 cups water (batter will be thin). Pour batter through strainer set over measuring cup. Heat 12-inch nonstick skillet over medium-high heat. Add 1 teaspoon oil to skillet; brush over skillet. Pour in 1/3 cup batter, immediately tilting skillet to allow batter to spread over bottom (if batter does not spread easily, thin with more water by teaspoonfuls). Cook until pancake is light golden on bottom, about 2 minutes. Turn pancake over and cook until bottom is light golden, about 1 minute. Transfer to paper towels. Repeat with remaining batter, adding 1 teaspoon oil to skillet for each pancake and stacking pancakes between paper towels. (Can be made 1 day ahead. Wrap layered with paper towels in foil and refrigerate. Heat foil packet in 300°F oven for about 15 minutes.) Sprinkle 2 tablespoons cheese over each pancake. Top each with 4 half-slices prosciutto. Sprinkle with pepper. Fold pancakes in half and then in half again, forming triangles. Transfer to plates.
Preparation Sift flour and salt into bowl. Add egg, then gradually whisk in 1 1/2 cups water (batter will be thin). Pour batter through strainer set over measuring cup. Heat 12-inch nonstick skillet over medium-high heat. Add 1 teaspoon oil to skillet; brush over skillet. Pour in 1/3 cup batter, immediately tilting skillet to allow batter to spread over bottom (if batter does not spread easily, thin with more water by teaspoonfuls). Cook until pancake is light golden on bottom, about 2 minutes. Turn pancake over and cook until bottom is light golden, about 1 minute. Transfer to paper towels. Repeat with remaining batter, adding 1 teaspoon oil to skillet for each pancake and stacking pancakes between paper towels. (Can be made 1 day ahead. Wrap layered with paper towels in foil and refrigerate. Heat foil packet in 300°F oven for about 15 minutes.) Sprinkle 2 tablespoons cheese over each pancake. Top each with 4 half-slices prosciutto. Sprinkle with pepper. Fold pancakes in half and then in half again, forming triangles. Transfer to plates.