Cut DLM French Boule in half horizontally. On bottom half, scoop out the inside leaving about a 1-inch shell. Leave the top un-scooped. Brush inside of both halves with 1 Tbsp olive oil. Spread 2 Tbsp olive spread on each half of loaf. Set aside top half.
Working with the bottom side, distribute tuna evenly over olive mixture and drizzle with remaining 2 Tbsp olive oil. Arrange tomato slices and onion over tuna. Season to taste with salt and pepper. Then, place egg slices over tomato. Place reserved top half on sandwich. Press down gently on sandwich and wrap tightly in plastic wrap. Place in refrigerator and weight the top down with something to help press sandwich and mingle flavors. Press for 2 to 24 hours. Before serving, bring to room temp and cut into wedges.