Time to put it all together. Move the dough from the fridge to a floured counter top. Then, roll the pie crust out until it’s about 16in (40.5cm) in diameter. Try to keep as close to a circle as possible by rotating the dough 15-30 degrees every pass of the rolling pin, much like rolling out dumpling wrappers. Now, move the pie crust to a baking sheet that's been covered with either a silicone mat or parchment paper. It's okay if it spills over the sides at this stage.
Spoon the frangipane filling into the middle of the crust and spread leaving about a 2.5-3in (6.4-7.5cm) border. The filling should only cover an area that fits on your baking sheet as that will be the final size of the galette.
When the frangipane is spread out, slice up each nectarine into 16 pieces. First, slice the nectarines in half, top-to-bottom, so you have an East and West hemisphere. Then, twist each side counter to each other, without bruising, to separate one side from the pit. From there, find the sharp bottom of the pit and use it to pry the pit from the other side of the nectarine. Now, slice each half into halves and then each quarter into halves and then each eighth into halves again until you have 16 slices. Repeat with the second nectarine. This should give you relatively equal pieces.
Next, arrange the nectarine slices any way you’d like. Pour them on and spread evenly for something rustic, or arrange them in a flower pattern for some extra wow! Gently fold the pie crust over the filling in segments, leaving the middle exposed.
Mix together your egg wash and spread it onto the crust. Make sure to get the sides of the galette as well, not just the top. And keep the coating light, otherwise you get scrambled eggs pooled on top of your crust. Then sprinkle some granulated sugar onto the egg wash if you want a little extra sweetness and crunch. When done, cover and pop the galette in the refrigerator for about 30-minutes.
While the nectarine and frangipane galette is chilling, preheat your oven to 425°F (218°C). Then bake for 35-45 minutes. If you want to add the glaze, for some shine on the fruit, now is the time to mix it up and baste the nectarines with a pastry brush. Let the galette cool for 10 minutes before moving it to a cutting board to slice.