Preheat oven to 350°. Line a rimmed baking sheet with parchment paper.
In a large skillet, melt butter over medium heat. Add onion, and cook until translucent, 4 to 6 minutes. Add bell pepper, and cook until softened, 3 to 5 minutes. Add garlic, and cook until fragrant, about 1 minute. Remove from heat, and transfer to a large bowl.
Add tomatoes, crawfish, cheeses, salt, and black pepper to onion mixture; stir until well combined. Divide mixture between bread halves, spreading into an even layer.
Bake until cheese is hot and melted, 8 to 10 minutes. Using a serrated knife, slice crosswise into servings. Serve warm.
Recipe by Louisiana Cookin' at https://louisianacookin.com/crawfish-bread-bites-2/