Position a rack in the center of the oven and preheat to 350°F.
Unfold the puff pastry onto a clean work surface and cut into 12 equal rectangles. Poke 3-4 holes in each with a fork. Transfer to a parchment-lined baking sheet and bake until golden and puffed, 13-15 minuets. Remove from the oven and let the puff pastry cool completely.
While the pastry cools, whip the cream until stiff peaks form. Using a spatula, fold the jam into the whipped cream until incorporated.
To assemble the napoleons, lay out four pieces of puff pastry. Top each with a thin layer of strawberry slices then a generous dollop of whipped cream. Spread the cream slightly to coat the strawberries and dust with confectioners’ sugar. Repeat another layer then top each stack with a final third piece of puff pastry. Dust once more with confectioners’ sugar and serve.