Caramelized Onion and Brie Tarts

24 pre baked miniature tart shells, bought or your own favourite recipe. 2 large onions , thinly sliced 2 tablespoons olive oil 2 tablespoons brown sugar 2[...]

1/4 cup margarine 1 large red onion , thinly sliced 8 slices Canadian bacon 4 large plain croissants, halved lengthwise or 4 large bagels , split and toasted[...]