If using refrigerated cooked crawfish tails, pat them dry with paper towels and roughly chop into bite-sized pieces if large. Separate the white parts of the green onions from the green tops; reserve greens for garnish.

Sweat onion and jalapeño

In a medium heavy-bottomed saucepan or skillet over medium heat, melt the butter. Add the diced yellow onion and the white parts of the green onions and cook, stirring occasionally, until softened and translucent, about 4–5 minutes. Add the jalapeño and minced garlic and cook 30–45 seconds until fragrant, taking care not to brown the garlic.

Make roux

Sprinkle the flour over the softened aromatics and stir to coat. Cook the flour for 1–2 minutes, stirring constantly, to remove the raw flour taste but do not let it darken noticeably.

Add milk and thicken

Slowly whisk in the whole milk and half-and-half in a steady stream to prevent lumps. Increase heat to medium-high and bring the mixture to a gentle simmer while whisking. Continue to simmer, whisking frequently, until the sauce thickens enough to coat the back of a spoon, about 4–6 minutes.

Incorporate cheeses

Reduce heat to low. Add the cream cheese and whisk until smooth. Add the shredded sharp cheddar and Monterey Jack a handful at a time, stirring between additions until fully melted and the sauce is smooth and velvety. Keep the sauce over low heat to avoid separation.

Season and finish

Stir in the cajun seasoning, smoked paprika, hot sauce (if using), lemon juice, kosher salt, and black pepper. Taste and adjust seasoning as needed. If the sauce becomes too thick, whisk in up to 2 tablespoons of milk to reach desired consistency.

Add crawfish and vegetables

Fold the chopped crawfish tails, diced tomato, and most of the green onion greens (reserve a little for garnish) into the queso. Warm gently for 2–3 minutes until the crawfish are heated through—do not boil. This will infuse the cheese sauce with crawfish flavor while keeping the seafood tender.

Finish and garnish

Remove from heat, stir in the chopped cilantro or parsley, adjust seasoning one last time, and transfer the queso to a warmed serving bowl. Sprinkle reserved green onion tops and a pinch of smoked paprika on top for color.

To Serve

Arrange wheat chips on a large platter or bowl. Serve the warm crawfish queso alongside or pour the queso into a shallow bowl set in the center of the chips. Offer lime wedges on the side for squeezing over individual portions.

For best results, keep the queso warm over a low heat or in a small slow cooker set to warm if serving for a crowd. Stir occasionally to prevent skin from forming.