Preheat your oven to 400°F. Remove the puff pastry from the freezer and let it thaw at room temperature for about 20-30 minutes until it's pliable but still cool—this makes it easier to cut without tearing. While the pastry thaws, line two baking sheets with parchment paper.

In a medium bowl, beat the room-temperature cream cheese until smooth and creamy, about 1-2 minutes. Add the egg yolk, 1/4 cup powdered sugar, lemon zest, vanilla essence, and a pinch of fine sea salt. Beat until well combined and fluffy, about 2-3 minutes. I like to use room temperature cream cheese here because it blends smoothly without lumps, which makes the filling silky and elegant.

In a small bowl, gently combine the raspberry jam and fresh raspberries, stirring just enough to distribute the jam evenly without crushing the berries too much. Set aside until ready to use.

On a lightly floured surface, lay out the thawed puff pastry and cut it into twelve 5-inch squares using a sharp knife or pastry cutter. Transfer each square to the prepared baking sheets, spacing them about 2 inches apart. Fold all four corners toward the center of each square, pressing them down gently but firmly to help them stay in place—the corners should overlap slightly in the middle. Using the tines of a fork, poke the center of each pastry square several times to prevent excessive puffing in that area.

In a small bowl, lightly beat the egg white with a fork until slightly frothy. Using a pastry brush, brush the entire surface of each pastry square with the egg white—this creates a beautiful golden finish when baked. Divide the cream cheese filling from Step 2 evenly among the twelve pastries, spooning it into the center of each one. Top each dollop of cream cheese filling with about a tablespoon of the raspberry mixture from Step 3, letting some raspberries and jam overlap slightly for visual appeal.

Bake the pastries in the preheated 400°F oven for 15-20 minutes, until they're puffed and golden brown. The pastry should be crispy and the filling set but still slightly soft. I like to rotate the baking sheets halfway through baking to ensure even browning on all pastries.

Remove the pastries from the oven and let them cool on the baking sheets for 5 minutes, then transfer them to wire cooling racks to cool completely, about 15-20 minutes. While they cool, whisk together the 1/2 cup powdered sugar and lemon juice in a small bowl until smooth and drizzle-able. Once the pastries have cooled, drizzle the lemon glaze over the top of each one in a thin stream, letting it pool slightly in the center and drip over the sides.