Essential oil of bergamot comes from the rind of an Italian citrus fruit that looks like an orange, but is believed to be a cross between a sweet lemon and a sour orange. The oil is what gives Earl Grey tea its distinctive citrus note. You can use the tea to infuse milk or cream and churn it into Earl Grey ice cream or Earl Grey crème anglaise. But if you want to isolate the delicate bergamot flavor from the strong black tea, buy yourself some bergamot oil. It's available at natural foods stores.
The second time I made this dish, for a recent dinner party, I didn't have time to make a pie crust. In a hurry, I tossed sliced apples with some flour, a little sugar, juice of a lemon and drops of bergamot oil, and threw them straight into the pan, topped with the crumble topping. Without a bottom crust, the tart became a pleasantly light finish to an otherwise heavy meal.
Now I think the easiest and tastiest method is to use a lot of buttery crumble topping.
