Preheat broiler to medium high.
Remove most of the soft, bread "guts" from each side of the baguette and place on a cookie sheet. Transfer the sheet to the oven and broil until golden, about 1-2 minutes.
Once the bread is toasted, combine the tuna, tapenade, lemon juice, EVOO, shallot, parsley and thyme in a bowl and season with a little black pepper.
Spread the tuna mixture over the dug-out part of the toasted baguette, top with the sliced tomatoes and Brie cheese and place under the broiler until the cheese has melted.