Saint André and Fingerling Potato Pies

Name: Saint André and Fingerling Potato Pies
Ingredients: 2 cups all purpose flour; 1 teaspoon salt; 3 /4 cup (1 1/2 sticks) chilled unsalted butter, cut into 1/2-inch cubes; 1 large egg; 2 tablespoons (or more) cold water; 1 pound white onions, halved lengthwise, thinly sliced crosswise (about 5 cups); 2 cups dry white wine; 1 /4 cup red wine vinegar; 1 /4 cup olive oil; 2 tablespoons tomato paste; 2 tablespoons sugar; 1 large fresh thyme sprig; 1 /4 teaspoon ground black pepper; 1 /2 Turkish bay leaf; 8 ounces fingerling or baby Dutch yellow potatoes; 2 large egg yolks; 2 /3 cups whipping cream; 1 /4 teaspoon salt; Pinch of ground black pepper; Pinch of ground nutmeg; 6 ounces Saint André cheese, cut into 6 slices