Heat the oven to 400°F (200°C) and line a baking sheet with parchment paper. Unroll the thawed puff pastry and cut each sheet into four equal rectangles or squares, making eight pieces total.

Place the pastry pieces on the prepared baking sheet. Prick the centers lightly with a fork, leaving the outer edges untouched so the borders can puff into visible layers.

Bake for 15–20 minutes, or until the pastry is deeply golden, crisp, and fully puffed. Transfer the pieces to a cooling rack and let them cool completely before filling.

Whip the cold heavy cream with 1/4 cup confectioners’ sugar and 1 teaspoon vanilla until firm peaks form. Stop mixing as soon as the cream holds its shape so it remains smooth rather than grainy.

Carefully split each cooled pastry horizontally into two layers. Spread approximately 1 tablespoon of seedless raspberry jam over the bottom layer of each pastry.

Pipe or spread the vanilla whipped cream over the jam, keeping the filling inside the pastry edges. Place the top pastry layer over the cream and press very gently.

Stir 1 cup confectioners’ sugar with 1 1/2 to 2 tablespoons milk or cream until the icing is smooth, thick, and spreadable. Add the optional 1/4 teaspoon vanilla, or add a tiny amount more liquid if the icing needs loosening.

Spread a thin layer of icing over each pastry. Refrigerate the assembled Flakies for 20–30 minutes before serving so the cream firms and the icing sets.