Thaw the puff pastry in advance of starting.
Roll out the puff pastry, cut into 4 to 6 inch (10 to 15 cm) squares, depending on how many you want to make. Make edges on them, and bake them according to package directions. When done, let cool a bit. You can do this part a few hours in advance, or proceed straight with the rest of the recipe.
Start heating oven to 200 C / 400 F / Gas Mark 6.
Wash the zucchini, cut into very thin round slices.
Spread a generous tablespoon or so of pesto sauce on top each square. Cover each with overlapping zucchini slices, brush them with the olive oil and pop into the oven until the zucchini is a very light golden brown -- about 7 minutes. Remove, and serve either right away, or let cool a bit first. Before serving, sprinkle very lightly with some fresh grated parmesan and pine nuts.