Take your pears and slice them up into thin slices and place into a medium bowl. Top the pears with brown sugar, vanilla, and lemon juice. Then add the nutmeg and cinnamon to the bowl and stir with a silicone spatula.
Mix that together and let macerate in a bowl.
Roll out the puff pastry sheet into a pie dish. Place the slices of pears into the bottom of the pie dish slightly overlapping each other. Pour the juice on top of them. If you want a pie lid or a lattice follow the Optional step below.
Preheat the oven to 400℉/200℃/Gas Mark 6.
Optional: If you want to make a lattice, follow these instructions. Roll out your extra pie dough into a 12” rectangle. Using a pizza cutter, knife, or pastry wheel, slice your pie dough into 12 even 1” strips. Take the pie dough strips and weave them over and under each other as necessary until the whole pie has a beautiful lattice on top. If you do not want to make a lattice, simply roll out the extra pie dough and make a simple pie lid and poke some holes into it or do not use a pie lid at all. Pinch the edges of the pie dough together and cut off the excess pie dough. Either crimp or flute the edges of the pie. Sprinkle the top with coarse sugar. If using a pie lid, make an egg wash to seal the pie together. Take an egg and 1 tbsp. of whole milk and whisk it together. Brush over the top of the pie lid and the sides of the base with a pastry brush of the pie and pinch together.
Bake the pear pie for 25 minutes. Add a heat shield then reduce the heat to 375℉/190℃/Gas Mark 5 and bake for another 35-40 minutes.
Remove from the oven and place on a cooling rack for a minimum of 1 hour. The longer that you let the pie sit, the more the filling will thicken as it cools.
Cover and store your leftover pie for up to 5 days in the refrigerator.