Begin by peeling and deveining the shrimp, then set aside. Dice the onion and bell peppers, and mince the garlic.
In your heavy-bottomed skillet or Dutch oven, melt the butter over medium heat until it starts to foam and smell nutty. Stir in the flour, then cook, stirring constantly, for 10-15 minutes until the roux turns a deep amber color and develops a rich aroma.
Add the diced onions and bell peppers to the roux. Cook, stirring occasionally, for about 8-10 minutes until the vegetables are tender and fragrant, and the mixture has thickened slightly.
Stir in the minced garlic, smoked paprika, cayenne pepper, thyme, and a pinch of salt. Cook for 1-2 minutes until the spices release their aroma and coat the vegetables evenly.
Pour in the broth, scraping up any browned bits from the bottom of the pan. Bring the mixture to a gentle simmer and cook for about 10 minutes until the sauce thickens and the flavors meld.
Add the peeled and deveined shrimp to the simmering sauce. Cook for 3-4 minutes, stirring gently, until the shrimp turn bright pink and are opaque.
Finish by squeezing in the fresh lemon juice and tasting for seasoning. Adjust salt or spices as needed to balance smoky heat with brightness.
Serve the Shrimp Étouffée hot over steamed rice or with crusty bread, garnished with chopped green onions if desired. The sauce should be thick, glossy, and fragrant with smoky spices and tender shrimp.