The keys to achieving razor-edged triangles: Let the sandwiches cool slightly, then slice with a serrated knife.
Recipe information
Yield
8 Servings
Ingredients
8
8
8
¾
¼
Preparation
Step 1
Preheat oven to 350°. Bake prosciutto on a parchment-lined baking sheet until it darkens and shrinks slightly, 6–8 minutes. Let cool (meat will crisp as it cools).
Step 2
Top 4 slices of bread with half of cheese, prosciutto (breaking to fit), watercress, then remaining cheese (it will bind as it melts) and bread; butter tops.
Step 3
Heat a large skillet over medium heat. Working in 2 batches, cook sandwiches, butter side down, pressing firmly, until bottom is golden brown. Butter tops, turn, and cook until golden brown and cheese is melted, about 4 minutes. Transfer to a wire rack; let cool slightly. Remove crusts and cut each sandwich into 4 triangles.
Step 4
DO AHEAD: Toasties can be cooked 2 hours ahead. Store uncovered at room temperature. Reheat before serving.