For the Crust:

1. Roll out the pie dough on a lightly floured surface until it will fit the base of a 9-inch round tart pan or a 14-by-4.5-inch rectangular tart pan, with a little bit of excess to create a crust up the sides.
2. Press the dough into the pan, and trim any excess around the edges. Place in the refrigerator to chill for at least 30 minutes before filling.
3. Preheat oven to 350°F.
4. Partially blind bake the crust. Press a piece of aluminum foil or parchment paper onto the surface of the crust, and fill with pie weights or dry beans. Bake for 10 minutes. Remove the foil, and bake for another 5 minutes.
5. Remove from the oven and let cool slightly. Keep the oven on.

For the Filling:

1. Heat 1 tablespoon of the olive oil in a large skillet over medium-high heat. Add red pepper slices and onions. Cook, stirring occasionally, until deep golden brown and caramelized, about 10-12 minutes. Season with salt and pepper to taste, and transfer to a large bowl.
2. Return the skillet to the heat, and add the remaining 1/2 tablespoon oil. Add the greens and cook, stirring often, until completely wilted and the liquid has evaporated, about 5 minutes. Transfer to the bowl with the onions and peppers, and stir to combine. Set aside to cool slightly.
3. In a small bowl, whisk together the eggs, milk, and 1/2 cup of the shredded cheese.
4. Spread the vegetable mixture on the bottom of the partially baked crust. Carefully pour the egg mixture over the vegetables. Top with the remaining 1/2 cup of shredded cheese, and a sprinkle of salt and pepper.
5. Bake until puffy and light golden brown on top, about 40-45 minutes. The egg mixture should not jiggle when you gently shake the pan.
6. Remove and set aside to let cool until just warm, about 10 minutes. Cut into slices and serve.