Turn broiler on low.
Put bread slices on baking sheet in single layer.
Place under the broiler for 3 to 5 minutes or until lightly browned.
Turn slices over and put back under the broiler to lightly brown the other side.
Pre-heat oven to 400°F.
Heat olive oil in a skillet over medium heat.
Add shrimp, onion and celery; cook for 1 minute stirring frequently.
Add the garlic and sprinkle the skillet with the Cajun seasoning and black pepper; cook for 1 minute stirring constantly; reduce heat to very low.
Add cream cheese, Parmesan and Fontina; stir until the cheese is blended and almost fully melted.
Top the toasted baguette slices evenly with the shrimp mixture.
Sprinkle with crushed red pepper and place in pre-heated oven for 10 minutes or until lightly browned and bubbly.
Serve immediately.