Heat the oven to 400 degrees F. Line a large baking sheet with parchment paper and set aside.
FOR THE CRUST
Combine the flours, cinnamon, and salt in a food processor by pulsing 3 times.
Place cubed butter into the processor and combine with flour by pulsing 5-6 times.
Add shortening and pulse 5-6 times.
Add cold water and vinegar slowly while pulsing. Mix until it is almost incorporated into a ball.
Flatten into a disc, wrap tightly in plastic wrap, and chill for 30 minutes. Meanwhile, make the filling.
FOR THE FILLING
While the crust is chilling, peel, core, and chop the apples. Place into a medium-sized bowl. Add sugar, flour, cinnamon, nutmeg, lemon juice, and lemon zest, then toss with a wooden spoon.
Let filling stand at room temperature until the crust is ready to be rolled out so that the apples can macerate (break down and create juice)
FOR THE TOPPING
In a medium-sized bowl, whisk together the flour, sugar, salt, and cinnamon. Add butter and using your fingers, quickly incorporate the butter into the dry ingredients. The butter pieces will be the size of rolled oats or small peas.
Roll out pastry dough into a 10-inch circle, or cut a few smaller circles out for single serving galettes and place onto the prepared pan.
Pour prepared apples into center of dough circle(s), leaving a 1.5 inch border around the edge. Top with quartered Rolos and topping mixture, then bring the edges of the dough up and over the apples, creating a pleated edge. Don't worry if it doesn't look perfect. A rustic appearance is a good thing!
Brush the crust with egg wash (1 egg and a teaspoon of water whisked together). If desired, sprinkle the crust with some granulated sugar.
Bake for 30-35 minutes or until galette edges are golden brown. (If you're making smaller servings, cooking time will be reduced to 15-20 minutes.)
Remove pan from oven and let caramel apple galette cool completely, then sprinkle the topping over the filling.