In a food processor, combine plain flour and fine table salt. Add the very cold, cubed unsalted butter, pulsing until the mixture resembles fine crumbs, about 10 seconds. Gradually add very cold water until the dough comes together, forming a disk. Wrap it in plastic and refrigerate for at least 1 hour to chill.

After chilling, roll out the dough on a floured surface until it's about 1/8-inch thick. Carefully transfer it to a quiche pan, pressing the dough into the edges. Dock the bottom with a fork to prevent bubbling, then refrigerate for another hour. Preheat your oven to 180°C/350°F and blind-bake the pastry for 20 minutes, covered with parchment, followed by another 10 minutes uncovered, until lightly golden.

While the crust is baking, toss the pumpkin cubes with olive oil and a pinch of salt in a large bowl. Spread them evenly on a baking sheet and roast in the preheated oven for about 20 minutes, or until the pumpkin is tender and slightly caramelized, stirring halfway through for even cooking.

In a mixing bowl, whisk together medium eggs, heavy cream, ground pepper, and garlic powder until smooth and fully combined. Make sure to blend well to create a creamy custard for your Roasted Pumpkin Quiche. Set this mixture aside while you assemble the filling with the roasted pumpkin.

Once the crust is pre-baked, layer the roasted pumpkin evenly on the bottom. Sprinkle the crumbled feta cheese over the pumpkin, ensuring even distribution for flavor in each bite. Carefully pour the egg custard mixture over the pumpkin and feta, allowing it to fill the spaces and coat the filling generously.

Return the assembled quiche to the oven and bake for approximately 40 minutes at 180°C/350°F. The filling should be set and lightly puffed, with a delicate golden top.

Once your Roasted Pumpkin Quiche is done, remove it from the oven and allow it to cool slightly for about 10-15 minutes. This resting time helps the quiche set further, making it easier to slice. Serve warm or at room temperature.