Dice the yellow onion, red bell pepper, green onions, celery, garlic, and parsley. Combine all the chopped vegetables in a large deli or storage container. Give it a good shake or mix to combine.
Heat olive oil in a large cast iron skillet over medium heat. Add the prepped vegetable mix and cook, stirring occasionally, until softened (I added about 3/4 the container and froze the rest). Be careful not to let the vegetables burn, lower the heat slightly if needed.
(Optional but Recommended) For added flavor and to protect your cast iron, you can transfer the cooked vegetables to a saucepan. Add the white wine and cook until it’s fully evaporated. This prevents the acidity from stripping your cast iron.
Return the vegetables to the cast iron skillet. On medium low heat, add butter and allow it to melt completely. Stir in the flour and cook, stirring constantly, until the flour develops a light golden color. Be careful not to burn it.
Slowly pour in the seafood stock, about ½ cup at a time, stirring constantly to maintain a smooth consistency and prevent the roux from splitting. Turn your heat up to medium to let it simmer for 5–10 minutes until slightly thickened.
Turn off the heat and stir in the heavy cream. Mix well to incorporate.
Stir in the crawfish tails, crab meat, shrimp, and cubed golden potatoes.
Grate in sharp cheddar cheese to taste, I like mine extra creamy, so I go generous. Add a capful of crab boil and season with Cajun seasoning to your liking. If your seafood wasn’t pre-boiled, use more seasoning to boost the flavor. (Tip: This dish shines when made with leftover seafood boil from the freezer.)
Drape the puff pastry sheet over the top of the skillet, trimming any long overhangs but leaving a bit extra to crimp around the edge. This helps keep the pastry in place while baking. Cut a small “X” in the center to allow steam to escape.
Place the skillet in a preheated 400°F oven. Bake for 35–40 minutes, or until the puff pastry is golden brown and crisp.