Preheat grill for medium-high heat.
Brush apple quarters with a neutral flavored oil and place on grill. Cook for 2-3 minutes turning each piece once. Remove from grill and place onto a clean cutting board.
Place naan on grill and cook one side for 2 minutes until toasted. Remove.
Slice apples into 1/2 thick slices. Brush each naan on the cooked side with olive oil. Layer with apples and brie, alternating between the two. Top with pecans or walnuts.
Place pizzas onto grill "uncooked" side down. Cook for 4-5 minutes until golden brown and cheese has melted. Remove from grill, drizzle each with warm maple syrup, and top with thyme. Slice and serve.