Step 1 Measure 1 cup water, the butter and salt into a heavy saucepan. Bring to a boil. When the butter is melted, remove the pan from the heat and add the flour all at once. Stir vigorously with a wooden spoon until completely mixed and blended.
Step 2 Return to the heat and cook and stir over low heat 5 to 6 minutes, to dry the mixture. The dough should be soft and should not stick to your fingers when pinched. The bottom of the pan should be covered with a thin crust, which is an indication that the dough has been sufficiently dried.
Step 3Transfer the dough to a bowl and let it cool for at least 5 minutes. Add 4 eggs one at a time, beating carefully after each addition so that the mixture is smooth before the next egg is added. The dough should be smooth, shiny and as thick and heavy as mayonnaise.
Step 4Heat the oven to 400 degrees. Coat a cookie sheet with butter and flour. Using a flan ring or any circular mold, mark an outline about 10 inches in diameter.
Step 5Spoon the pate a choux into a pastry bag. Squeeze out a ring about 1 inch wide following the outline. Squeeze another ring inside the first, then squeeze a ring on top of the others.
Step 6Brush with remaining egg, lightly beaten. Sprinkle with sliced almonds. Let choux stand about 20 minutes.
Step 7Bake 45 minutes. Turn off the oven and open the oven partially. Let the ring stand in the oven for 1 hour so it cools and dries.