Add 12 tablespoons cold cubed unsalted butter to the flour. Using a pastry cutter, two forks, or your fingertips, cut the butter into the flour until the mixture resembles coarse crumbs with pea-sized bits of butter remaining.

Add ice water

Sprinkle 6 tablespoons ice water over the mixture, 1 tablespoon at a time, gently tossing with a fork after each addition. Add only enough to bring the dough together — it should hold when pressed but not be sticky. You may need 5–6 tablespoons.

Form and chill

Gather the dough into a flat disc, wrap tightly in plastic wrap, and refrigerate for at least 30 minutes (up to 2 hours).

Roll out

Preheat the oven to 375°F (190°C). On a lightly floured surface, roll the chilled dough to about 1/8-inch (3 mm) thickness. Cut into rectangles or circles for individual pastries (about 4" x 5" rectangles or 3.5" rounds). You should get 8–10 pastries depending on size.

Egg wash

Beat the large egg with 1 teaspoon water to make an egg wash. Place cut dough on a parchment-lined baking sheet. Brush edges lightly with egg wash.

Caramel Almond Filling

Toast almonds

If your sliced almonds are not toasted, spread 1.5 cups sliced almonds on a baking sheet and toast in the oven for 6–8 minutes until lightly golden and fragrant. Let cool.

Make caramel

In a medium, heavy-bottomed saucepan, combine 1 cup granulated sugar and 2 tablespoons water. Place over medium heat and without stirring, allow the sugar to dissolve and begin to caramelize. Gently swirl the pan occasionally to ensure even browning. Watch closely — when the sugar reaches a deep amber color (about 8–10 minutes), remove from heat.

Finish caramel

Carefully and slowly pour 3/4 cup warmed heavy cream into the caramel while whisking (the mixture will bubble vigorously). Stir in 2 tablespoons unsalted butter and 1/4 teaspoon fine sea salt until smooth. If using, add 1/4 teaspoon almond extract. Let the caramel cool 5–8 minutes until slightly thickened but still pourable.

Combine with almonds

Fold the toasted sliced almonds into the warm caramel, coating them evenly. Reserve a tablespoon of caramel for drizzling if desired.

Assembly & Baking

Fill pastries

Spoon about 2–3 tablespoons of the caramel-almond mixture onto the center of each pastry piece, leaving a 1/2-inch border. For rectangles, fold one side over to create a pocket or leave open for a tart-like pastry. Press edges to seal or crimp with a fork. If sealing, brush the top lightly with egg wash and cut a small vent if closed.

Bake

Bake in the preheated 375°F (190°C) oven for 18–22 minutes, rotating halfway, until pastry is golden brown and caramel is bubbling lightly. If caramel begins to darken too quickly, cover loosely with foil for the last few minutes.

Cool and finish

Remove pastries to a wire rack and let cool 10–15 minutes. If desired, dust with 2 tablespoons powdered sugar, drizzle reserved caramel over the tops, and sprinkle a tiny pinch (about 1/4 teaspoon) of coarse sea salt on several pastries to enhance flavor.