Using ingredient filling cook onions in butter until translucen let cool

Onion And Cheese Quiche

• 3 onions thinly (very sliced)
• 3 eggs
• 1 salt pepper
• 1 all ingredients should be (very cold)
• 1 filling cook onions in butter until translucen let cool
• 1 roll out dough
• 250 gr flour
• 240 ml cream (heavy)
• 240 gr swiss (grated)
• 110 gr butter