Follow instructions for your store-bought pie crust. You’ll want to “blind bake” it, meaning cook it in your tart or pie pan without any filling first. This probably means baking at 400 degrees F) and arranging the pastry with edges reaching up the side of the pan. Use your thumb and forefinger to crimp the edges. Prick with a fork and bake for approximately 15 minutes.
Meanwhile, combine eggs and milk in a large bowl and whisk for 3-5 minutes; the eggs should be fluffy. Add salt, pepper and dill. Stir briefly then add your remaining ingredients (onions, cheese, ham).
Bring pastry out of oven and pour in egg mixture. Reduce temperature to 375 degrees F and return quiche to the oven for 25-30 minutes.
Allow to cool for 5 minutes; serve warm or room temperature.