Remove the puff pastry sheets from the freezer and let them thaw in the refrigerator for about 30 minutes.
Take one pastry sheet at a time. Dust dough and your work surface. Gently re-roll each pastry until it’s uniformly about 3 mm thick, and 13X9.5-inch/33X23cm. This ensures an even thickness for a consistent rise. Once re-rolled, refrigerate pastry until you’re ready to use them.
Raspberry Jam Lattice Pastry
For the bottom pastry sheet, prick it with a dough docker or a fork. Do not prick the 3 remaining puff pastry sheets.
Spread a fair amount of the raspberry jam over the pricked pastry; freeze to set.
Flour your lattice dough cutter. Turn the second puff pastry sheet into lattice design.
Carefully, drap it over the raspberry jam. Trim off excess dough. Keep it refrigerate until ready to bake.
Baking
Preheat fan oven to 350ºF/180ºC. For a more even rise, place a sheet of parchment paper and a baking tray on top of your pastry as well.
Bake for 30 minutes. Remove the baking tray and parchment – put back in th oven and continue baking for 10 minutes more.
Cutting Puff Pastry Sheets
In the mixing bowl, gather the mascarpone, heavy cream, sugar, vanilla and lemon zest–refrigerate. Cut 2 pastry sheets into two 4-inch/10cm wide bands.
Cut each band into 6 portions. So, you should end up with 24 servings.
Do likewise with the raspberry jam lattice pastry sheet. Keep everything at room temperature.
Montage
Whip the heavy cream-mascarpone mixture to medium-firm peaks.
Pipe out 5 dollops of chantilly on the first 12 pastries. Fill the gaps with raspberries.
Drizzle some raspberry jam on top.
Add another tier with the remaining pastries, chantilly and fruits.
Enclose mille-feuille with the raspberry jam lattice pastries.
Storage
Mille-feuille is best enjoyed fresh because its signature crisp, flaky layers can soften as the moisture from the pastry cream seeps into the puff pastry over time. While many recipes mention that you can store a mille-feuille in an airtight container in the refrigerator for up to 2–3 days, the quality—especially the contrast between the crisp pastry and the smooth cream or chantilly—declines noticeably after about 24 hours. For optimal texture and flavor, it’s ideal to eat it within 12 hours of assembling it.