Preheat the oven to 375 F.
Place potato slices in a large bowl add 2 tbsp olive oil and season with salt and pepper. Mix well.
Line a baking sheet with parchment paper, arrange all potato slices neatly on paper. It's ok if they overlap. Bake potato slices for 15-20 min, or until the edges are getting crispy and light golden. They don't have to be fully cooked.
While the potatoes cook prepare the zucchini.
In a medium bowl add 1/2 cup flour, a tsp salt a generous amount of fresh ground pepper and a pinch or two of oregano. Mix well. Add the zucchini slices and make sure they are lightly coated with the flour mix.
Heat 2-3 tbsp olive oil in a frying pan. Fry the zucchini slice for 3-4 min, until they are light golden. Place slices on a paper towel rimmed plate. Set aside.
Make the cheese filling
In a bowl mix the ricotta, a tbsp of half & half (or heavy cream)and the philadelphia cheese. Mix well , making sure cheese mix is smooth. Add your fresh herbs, the olive oil the salt, the chili pepper flakes and the ground pepper. Mix well and set aside.
Preheat oven to 425 F.
Assemble
On a lightly floured work surface, roll the dough into a 12" circle. Transfer the dough to a parchment-lined baking sheet.
Spread 1/2 of the cheese mixture over the dough, leaving a 2"-wide bare strip along the perimeter.
Add a layer of potato slices. Add a layer of zucchini slices. add small pieces of the cheese mixture all around, try to spread it lightly.
Add a layer of zucchini and potatoes alternating each other. Add the remaining cheese mixture on top in small little dollops.
Fold the bare edges of the dough into the center.
Brush the exposed edges of the crust with egg wash. Sprinkle parmesan cheese all over crust. Sprinkle some fresh ground pepper as well.
Bake galette for 25 to 30 minutes, until the crust is golden brown and the filling is bubbling.
Remove the galette from the oven and allow it to cool for 5 to 10 minutes before serving.
Sprinkle some finishing salt, chili pepper flakes and a little chopped all over galette and serve. It can be enjoyed in room temperature as well.