* Preheat oven to 350ºF.
* Melt butter in large pan over medium heat. Add onions and cook, stirring frequently, for 15-20 minutes until caramelized. If onions begin to stick to the pan, add 1-2 Tbsp. water during cooking. Remove from heat and stir in 1/2 tsp. each salt and pepper.
* In a small bowl, mix together olive oil, thyme, and remaining salt and pepper. Brush both sides of bread slices with oil mixture and place on sheet pan. Bake for 12 minutes, turning once halfway through baking.
* Remove sheet pan from oven, and top each toasted bread slice with 1 Tbsp. caramelized onions and one slice of Ile de France Le Brie.
* Return crostini to oven for 2-3 minutes, or until cheese melts slightly. Serve warm.
* Serves 6