Tender, buttery layers of pastry topped with cinnamon-y apple filling and finished with a rich, sweet glaze: sounds like the perfect "fancy" breakfast, doesn't it? Bonus: this treat is made with our Gluten-Free Measure for Measure Flour, so it's ideal for any crowd: those good with gluten, and those avoiding it.
Preheat the oven to 350°F. Lightly grease (or line with parchment) a large baking sheet.
First layer: In a medium-sized mixing bowl, combine the butter, flour, and salt, working the butter into the flour with a pastry blender or fork, your fingers, or a mixer. Mix until everything is crumbly, then stir in the water. The dough will become cohesive, though not smooth.
Divide the dough in half. Wet your hands, and shape each piece of this wet dough into a rough log. Pat the logs into 10" x 2 1/2" rectangles on the sheet, leaving about 4" between them, and 2" on each side for expansion.
Second layer: In a medium-sized saucepan, bring the water and butter to a boil. Stir until the butter melts, then add the flour (and salt, if you're using it) all at once. Stir the mixture with a spoon until it thickens, begins to steam, and leaves the sides of the pan; this will happen very quickly.
Transfer the stiff batter to a mixing bowl, or the bowl of an electric mixer. Beat it at medium speed for 30 seconds to 1 minute, just to cool it down a bit.
Add the eggs one at a time, beating well after each addition; beat until the batter loses its "slimy" look, and each egg is totally absorbed.
Mix in the vanilla extract.
Divide the batter in half. Spread half the batter over one of the dough strips on the pan, covering it completely. Repeat with the remaining batter and dough.
With a spatula (or your wet fingers) spread the batter until it completely covers the entire bottom layer of dough. Smooth it out as best you can.
Bake the pastry for 50 minutes to 1 hour, or until it's golden brown. Remove it from the oven, and transfer each pastry to a rack.
While the pastry is baking, make the topping: Toss the grated apple with the lemon juice in a saucepan. Whisk together the sugar, cornstarch, salt, and cinnamon, and add to the pan, stirring to combine. Cook over low heat, stirring frequently, until the apple starts to release its juice. Increase the heat to medium, and bring to a simmer. Simmer, stirring, until the mixture thickens, 1 to 2 minutes; a spatula drawn across the bottom of the pan should leave a track that doesn't readily fill in. Remove from the heat, and set aside to cool to room temperature.
Spread each warm pastry with half the topping. Sprinkle with nuts. Allow the pastries to cool completely before adding the icing.
To make the icing: Mix together all of the icing ingredients. Drizzle over the pastries once they're cool.
Pastries are best served the day they're made. If you plan on baking ahead, don't ice the pastries immediately. Once they're completely cool, wrap loosely in plastic. Add the icing just before serving.
Be aware: some of your baking ingredients can be a hidden source of gluten. Learn more at our blog post: For gluten-free baking, think beyond just flour. For additional information on King Arthur-produced products, read the complete details of our allergen program, including our contact-prevention practices.
