Brush chicken breasts with oil and season with salt and pepper.

Grill chicken breasts until a meat thermometer inserted into the thickest piece reads 165°F (74°C) – about 5-7 minutes on each side. Remove from heat and let cool for 5 minutes. Slice chicken on the diagonal into 1/4 inch slices and set aside. This step can be done up to 24 hours ahead – refrigerate chicken until needed.

Slice baguette on the diagonal into 1/2 inch slices. Grill or toast slices until golden brown. Arrange on a large cookie sheet or two smaller cookie sheets, allowing for a little space between toasts.

Rub one side of each toast with the garlic and spread with a little of the mayonnaise. Top with a few arugula leaves. Top with one or two chicken slices (depending on size).

Slice brie into thin slices (approx 1/6 inch thick), leaving rind on. Place brie slices on top of chicken.

Place chicken brie crostini under broiler for 5-7 minutes or until cheese is melted and bubbling. Transfer crostini to a serving platter; top with a spoonful of fruit preserve and garnish with thyme sprigs. Serve warm.