1. Prepare the Cherry Filling (The Heart of the Pastry):

• Combine Ingredients: In a medium saucepan, gently combine the pitted cherries (fresh or frozen), granulated sugar, cornstarch, lemon juice, and pinch of salt. Stir well to ensure the cornstarch is evenly distributed and doesn’t form lumps. If your cherries are very large, you might consider halving them for a more manageable bite.
• Cook Until Thickened: Place the saucepan over medium heat. Bring the mixture to a gentle simmer, stirring frequently to prevent sticking and burning, especially as it begins to thicken. Continue to cook, stirring, for about 5-8 minutes, or until the sauce has visibly thickened and turned glossy. The cherries should be tender but still hold their shape. You’ll know it’s ready when the mixture coats the back of a spoon and appears translucent.
• Cool and Flavor: Remove the saucepan from the heat. Stir in the vanilla extract and almond extract (if using). Set the filling aside to cool completely. This is a crucial step; adding hot filling to puff pastry will cause the butter in the pastry to melt prematurely, resulting in a greasy, flat pastry rather than a light and flaky one. You can speed up the cooling process by transferring the filling to a shallow bowl and placing it in the refrigerator.

2. Prepare the Streusel Topping (The Crown of Crunch):

• Combine Dry Ingredients: In a medium bowl, whisk together the all-purpose flour, granulated sugar, and ground cinnamon (if using). If adding chopped nuts, stir them in now.
• Cut in the Butter: Add the cold, cubed unsalted butter to the dry ingredients. Using your fingertips, a pastry blender, or even a fork, work the butter into the flour mixture. The goal is to break down the butter into small, pea-sized pieces, coated in flour. The mixture should look like coarse crumbs. Be careful not to overwork it; you want distinct pieces of butter remaining, as this contributes to the crispness.
• Chill (Recommended): Place the bowl of streusel topping in the refrigerator while you prepare the pastry. Keeping the streusel cold will help it maintain its crumbly texture during baking.

3. Assemble the Cherry Streusel Pastries:

• Preheat Oven & Prepare Baking Sheets: Preheat your oven to 400°F (200°C). Line two large baking sheets with parchment paper. This prevents sticking and makes cleanup a breeze.
• Prepare Puff Pastry: Gently unfold your thawed puff pastry sheets on a lightly floured work surface. If your sheets are very thick, you might want to roll them slightly thinner, to about 1/8-inch thickness, but most store-bought sheets are ready to use.
• Cut the Pastry: Using a sharp knife or a pizza cutter, cut each puff pastry sheet into desired shapes. Popular choices include:

  • Squares: Cut each sheet into 4 or 6 equal squares (e.g., 4-inch squares).
  • Rectangles: Cut into rectangles (e.g., 3×5 inches).
  • Circles: Use a round cookie cutter.
    Place the cut pastry pieces onto the prepared baking sheets, leaving about 1-2 inches of space between them to allow for puffing.

• Score the Pastry (Optional but Recommended for a Border): For a neat border, use a sharp paring knife to lightly score a line about 1/2-inch to 3/4-inch in from the edge of each pastry piece, being careful not to cut all the way through. This creates a defined rim that will puff up around the filling.
• Dock the Center: Gently prick the area inside the scored border with a fork a few times. This helps prevent the center of the pastry (where the filling will go) from puffing up too much, creating a well for the cherries.
• Prepare Egg Wash: In a small bowl, whisk together the large egg and 1 tablespoon of water or milk until well combined.
• Brush with Egg Wash: Lightly brush the scored borders (or the entire surface if not scoring a border) of the pastry pieces with the egg wash. This will give them a beautiful golden color and a slight sheen. Avoid letting large pools of egg wash accumulate.
• Add the Cherry Filling: Spoon a portion of the cooled cherry filling into the center of each pastry piece, within the scored border if you made one. Be careful not to overfill, as this can cause the filling to spill out during baking. About 1-2 tablespoons per pastry is usually a good amount, depending on the size of your pastry cuts.
• Top with Streusel: Generously sprinkle the chilled streusel topping over the cherry filling, covering it well. Gently press the streusel down slightly to help it adhere. Some streusel may fall onto the egg-washed border, which is perfectly fine.

4. Bake to Golden Perfection:

• Bake: Place the baking sheets in the preheated oven. Bake for 18-25 minutes, or until the pastries are deeply golden brown, puffed up, and the streusel is crisp and lightly browned. The exact baking time will depend on your oven and the size of your pastries. If you notice the streusel or edges browning too quickly, you can loosely tent the pastries with aluminum foil for the last few minutes of baking.
• Cool Slightly: Once baked, carefully remove the pastries from the oven and let them cool on the baking sheets for about 5-10 minutes. This allows the filling to set a bit more. Then, transfer them to a wire rack to cool further. They are delicious warm, but allowing them to cool a bit more prevents a burnt tongue and helps the flavors meld.

5. Apply Optional Glaze (The Finishing Touch):

• Prepare Glaze: Once the pastries have cooled for at least 15-20 minutes (they should be warm, not hot), prepare the glaze. In a small bowl, whisk together the sifted powdered sugar and 1 teaspoon of milk, cream, or lemon juice. Add more liquid, a few drops at a time, until you achieve a smooth, drizzlable consistency. It should be thick enough to hold its shape but thin enough to flow off a spoon.
• Drizzle: Using a spoon or a piping bag with a small round tip (or even a zip-top bag with a tiny corner snipped off), drizzle the glaze over the warm pastries in a zigzag pattern or any design you like.
• Set: Allow the glaze to set for about 10-15 minutes before serving.