01 - Preheat the oven to 400°F. Line a baking sheet with parchment paper.
02 - Roll out the puff pastry on a lightly floured surface. Cut into 12 equal rectangles and arrange them on the prepared baking sheet. Sprinkle evenly with granulated sugar. Place a second sheet of parchment paper over the rectangles and set another baking sheet on top to weigh them down and prevent excessive puffing.
03 - Bake for 15 to 20 minutes until the pastry is crisp and deep golden brown. Transfer to a wire rack and let cool completely.
04 - In a mixing bowl, whisk the ricotta until smooth and creamy. Add the powdered sugar, lemon zest, lemon juice, and vanilla extract, then stir until well combined.
05 - In a separate chilled bowl, whip the heavy cream to stiff peaks. Gently fold the whipped cream into the ricotta mixture in two additions until evenly incorporated. Refrigerate until ready to assemble.
06 - Spread or pipe a generous layer of lemon ricotta cream onto six of the pastry rectangles. Place a second rectangle on top of each to form six two-layer mille feuille.
07 - Dust the top pastry layer of each with powdered sugar and finish with a scattering of fresh lemon zest. Serve immediately.