Heat 2 Tablespoons olive oil over medium-high heat in a medium size sauté pan. Sauté chicken breast until cooked through and juices run clear. Let rest and slice.
Brush one side of each slice of bread with olive oil. Turn slices over and generously spread the Roasted Garlic Onion Jam over each slice. Layer arugula, sliced chicken and Brie cheese over four of the slices. Top with remaining slice of bread (olive oil side out). Cook sandwiches in a panini maker until golden brown and cheese melts.