Preheat the oven to 350 °F (177°C). Spray a 9X13-inch baking dish with nonstick cooking spray. Set aside.
Make the Sauce:
In a medium saucepan over medium heat, melt butter (3 tablespoons). Whisk flour (3 tablespoons) and stir until the butter and flour are well combined. Continue to cook, stirring constantly, for 1 minute to remove the flour taste.
Remove the skillet from heat and whisk in broth (2 cups). Place back on heat and cook, stirring constantly, until the mixture comes to a boil, has thickened and is bubbly (this step is imperative! Be sure the sauce comes to boil. If your sauce is still on the thin side, continue to boil until it's thick enough to coat the back of a spoon.) Cool sauce for 3-5 minutes. (Don't skip this step if the sauce is too hot and you add the sour cream it will curdle it). Add sour cream (1 cup), chilies (1 can), and 1 cup Monterey Jack Cheese and stir until the sauce is smooth and the sour cream is completely dissolved. Set aside.
Make the Filling:
In a large skillet, melt butter (2 tablespoons) over medium heat. Add chopped onion (1 cup), jalapeno (1), and garlic (4 cloves), and sauté until slightly softened about 2 minutes. Add mushrooms (8 ounces) and continue to saute until tender, 5-8 minutes. Add shrimp (1 pound) and continue to saute for 2-3 minutes or until pink just start to turn pink. Remove from heat and stir in salt (1 teaspoon), pepper (1/2 teaspoon), cumin (1 teaspoon), chili powder (1 teaspoon), and fresh cilantro (1/2 cup). Add one cup of prepared sauce and stir to combine.
Assembly:
Lay tortilla on a flat surface and spoon 1/3 to 1/2 cup of the shrimp mixture in the center, roll tightly and lay seam side down into the prepared baking dish. Repeat with remaining tortillas and shrimp mixture. Pour the cream sauce evenly over the top and sprinkle 1 1/2 cups cheese evenly over top. Place in preheated oven and bake, covered, until lightly golden and bubbly, about 30 minutes.
Remove from the oven and let the enchiladas sit for 10 minutes before serving. Garnish with fresh chopped cilantro.
Notes
Want to turn up the heat? For spicy shrimp enchiladas, add a couple of finely chopped fresh jalapeños to the sauce, use the spicy version of canned green chiles, or swap Monterey Jack for Pepper Jack cheese. You can mix and match depending on how bold you want to go.
Jalapeños vary a lot in heat. Most of the spice lives in the ribs and seeds, so give a tiny nibble before adding them and adjust to your comfort level.
Green chiles add flavor without overpowering. I love using fire-roasted chopped green chiles for color and gentle heat. They warm up the sauce without changing its creamy white color — spices like cayenne or chipotle can turn the sauce slightly pink.
Don’t feel locked into shrimp only. This filling works beautifully as a seafood combo. Try adding a little jumbo lump crab for crab-and-shrimp enchiladas, or substitute bay-size scallops for part of the shrimp.
Flour tortillas make this recipe easier. While traditional enchiladas are made with corn tortillas, flour tortillas roll easily without pre-cooking and hold up better during baking and reheating. They also let the creamy shrimp filling shine without competing flavors.
Choose shrimp wisely. Since the shrimp are chopped, you have flexibility — buy what looks freshest or is on sale. Avoid very small “popcorn” shrimp; they get lost in the filling and have less flavor than medium or large shrimp.
Shell-on shrimp are often a better buy. Shrimp frozen in their shells are better protected from freezer damage and usually have better texture. Peel and devein them at home if you can.
Don’t rush the sauce. This creamy sauce is similar to shrimp enchiladas suizas. Start by cooking the butter and flour just until the raw flour taste is gone (1–2 minutes) — no need to brown it.
Let the sauce fully thicken before moving on. Once the broth is added, bring it to a boil and stir constantly until it reaches a gravy-like consistency. Skipping this step can leave you with a thin, soupy sauce.
Add sour cream and cheese off the heat. Let the sauce cool slightly before whisking in sour cream so it stays smooth and tangy. Monterey Jack melts beautifully here, adding richness and those irresistible cheese pulls when you serve.