To make the crust, cook the potatoes in the oven, or on the stove top in boiling water, or in the microwave until almost fork tender (not all the way). Allow to cool completely. Carefully peel the potatoes with a knife and shred with a box grater. Set aside.

In a large bowl, combine the flour, sugar and salt. Cut in the butter and shortening with a pastry blender, a potato masher, two knives or your hands, until it resembles coarse crumbs the size of peas. Fold in the grated potatoes, shredded cheese, crumbled bacon and chives. Add the ice water, a tablespoon at a time, mixing with a rubber spatula by hand until the dough comes together. It should be moist, but not too wet. Divide the dough in half and wrap the dough in plastic wrap. Allow to chill in the fridge for about 1 hour or overnight.

Preheat oven to 350° F. Cook the potatoes in the oven, or on the stove top in boiling water, or in the microwave until fork tender. Allow to cool completely and then dice. Set aside.

To make the filling, heat a large skillet over medium-high heat with 1 tablespoons oil. Once hot, throw in the sliced sausage and cook, stirring until browned and crispy, about 3 to 4 minutes. Remove sausage and set aside. Add in the cooked diced potatoes from earlier and spread out in a single layer. Cook until browned and crispy. Season with 1/2 teaspoon salt, 1/2 teaspoon pepper, garlic and onion powder and rosemary. Remove from skillet and set aside. Add the remaining tablespoon of oil to the skillet and stir in the veggies. Season with the remaining salt and pepper. Sauté for about 5 minutes until soft and just beginning to caramelize. Remove from heat and allow to cool down.

On a well floured work surface, roll out 1 of the dough discs into a large circle, about 1/2 an inch thick. Place the rolled dough into a 9-inch pie dish. Fill the pie with the cooled veggies, potatoes, and sausage. In a medium bowl, whisk together the eggs, milk, and a pinch of salt and pepper until completely whisked. Pour the eggs into the pie over the fillings. Top with cheese.

Roll out the second dough disc and place over the pie. Trim the edges as needed and fold under the bottom crust. Crimp the edges all around to seal. With a pairing knife, cut a few slits on top to release steam. Brush with egg wash and bake for about 30 to 35 minutes or until golden brown. Remove from oven and allow to cool down slightly before slicing. Enjoy!