Heat oven to 350°F Place 1 cup flour in large bowl; cut in 1/2 cup butter with pastry blender or fork until mixture resembles coarse crumbs. Stir in 2 tablespoons water with fork until flour mixture is just moistened. Shape dough into a ball. Pat dough into 10-inch circle on ungreased baking sheet. Set aside.
Combine 1 cup water and 1/2 cup butter in 2-quart saucepan. Cook over medium heat until mixture comes to a full boil and butter is melted (6 to 8 minutes). Remove from heat; stir in 1 cup flour and 1 teaspoon almond extract. Reduce heat to low. Cook, stirring constantly, until mixture forms a ball (about 1 minute). Remove from heat.
Add 1 egg at a time, beating with wire whisk or wooden spoon after each addition until smooth and glossy.
Spread egg mixture over pastry circle. Bake for 50 to 55 minutes or until surface is crisp and golden. Cool completely. (Topping rises during baking and shrinks during cooling, forming custard-like layer.).
Combine powdered sugar, 1 tablespoon butter and 1/2 teaspoon almond extract in small bowl until well mixed. Add enough milk for desired glazing consistency.
Drizzle glaze over puff; sprinkle with almonds.
Wrap coffee cake puff in plastic food wrap or aluminum foil; refrigerate up to 2 days.
Lemon Pecan Puff: Omit almond extract in topping. Substitute 2 tablespoons fresh lemon juice and 2 teaspoons freshly grated lemon peel. Omit almond extract and milk in glaze. Substitute 2 tablespoons fresh lemon juice. Omit sliced almonds. Sprinkle puff with 1/4 cup chopped pecans.
Maple Pecan Puff: Omit almond extract in topping. Substitute 1 teaspoon maple extract. Omit almond extract in glaze. Substitute 1 teaspoon maple extract. Omit sliced almonds. Sprinkle puff with 1/4 cup chopped pecans.