In a large bowl, mix together shrimp, tomatoes, green onion, olive oil, egg whites, seafood seasoning, and garlic powder. Set aside.
Brush olive oil over the slices of baguette and place baguette slices onto a baking sheet and place in oven until lightly toasted on one side.
Whisk together the mayonnaise and chipotle puree. Spread mixture evenly over toasted baguette slices. Then, top that with about a tablespoon of the shrimp mixture.
Return bruschettas to the oven for 8 to 10 minutes, or until heated through and lightly browned. Garnish with fresh basil.