Preheat the oven to 375F. Melt the butter and oil together in a large skillet and add the diced bacon. Cook until the bacon is halfway cooked.

Add the thyme, onion and salt to the skillet. Cook on medium-low heat until the onions are completely translucent and caramelized. This will take around 30 minutes. Remove from heat and allow to cool slightly.

Combine 2 eggs and the half and half in a bowl. Add the caramelized onion mixture and the freshly ground black pepper.

Roll out the puff pastry in a buttered pie or glass dish. (Make sure the pastry has four edges in order to hold the onion mixture.)

Add the mixture to the pastry and bake for 35 minutes or until the crust and top are slightly browned.

Allow to cool, then slice and serve.

More recipes with caramelized onions on Food Republic:

Caramelized Onion and Prosciutto Macaroni and Cheese

Caramelized Onion and Beef Loco Moco

Ham, Caramelized Onion and Gruyère Pizza