To make the spinach and mushroom quiche, combine the ingredients for the dough and knead with a food processor or your hands for at least 5 minutes to form a compact, elastic dough.
Let the dough rest in a small sealable bowl for 1 hour. Preheat the oven to 200 °C bottom heat. Roll out the dough large enough to cover the bottom and sides of the selected baking dish.
Line the pan with the dough, pressing the edge well. Prick the bottom a few times with a fork, place a piece of baking paper cut to size inside and sprinkle the dried chickpeas on top so that the bottom is completely covered.
Bake for 15 minutes. Let cool a bit and remove the baking paper with the sprinkled legumes. Turn oven to 200 °C top and bottom heat.
Clean mushrooms and cut into not too small pieces, cut onion into rings, wash spinach. Fry the mushrooms in hot olive oil until brown, add onion and fry as well.
Add spinach and continue frying until the leaves have collapsed. Place eggs in a bowl and whisk with salt and pepper.
Spread the mushroom and spinach mixture in the pan, pour egg mixture over the top and bake for 15-20 minutes until the egg mixture is set. Serve the spinach and mushroom quiche with salad.