Preheat the oven to 200°C (390°F) using conventional oven settings (top and bottom heat). Wash or peel the pumpkin, remove the seeds, and dice the flesh. Trim, wash, and quarter the Brussels sprouts. Peel and slice the onion.

Place the vegetables on a baking sheet, season generously with salt and pepper, and pre-cook in the oven for 15 minutes. Then reduce the oven temperature to 180°C.

Meanwhile, whisk the eggs in a large bowl, stir in the sour cream and cheese, and season generously with salt and pepper.

Grease a quiche dish with a little oil or butter, roll out the quiche dough onto a rolling pin and carefully unroll it over the quiche dish. Press the dough into the corners, pull it up the sides, and trim any excess.

Prick the pastry base with a fork. Then spread the pre-baked vegetables over the pastry and evenly distribute the egg mixture on top.

Bake the pumpkin quiche for 45 to 50 minutes at 180°C in a preheated oven until the egg mixture is set and has a golden brown color.