Preheat oven to 350°. Place flour in a bowl; cut in butter until crumbly. Sprinkle with water; toss with a fork until dough holds together when pressed. Divide dough in half. On greased baking sheets, press each portion into 12x3-in. rectangle.
For topping, in a saucepan, heat butter and water to a rolling boil. Add flour and salt all at once and beat until blended. Cook over low heat, stirring vigorously until mixture pulls away from sides of pan and forms a ball. Remove from heat; let stand 5 minutes. Add eggs, one at a time, beating well after each addition until smooth. Add extract; continue beating until mixture is smooth and shiny. Spread half of the mixture over each rectangle.
Bake until puffed and golden brown, about 1 hour. Cool on pans 10 minutes.
Mix first four icing ingredients until smooth; spread over warm pastries. Sprinkle with almonds.
To toast nuts, bake in a shallow pan in a 350° oven for 5-10 minutes or cook in a skillet over low heat until lightly browned, stirring occasionally.