Preheat the oven: Set to 375°F (190°C). Grease a 9x13-inch baking dish or use an oven-safe skillet to keep it one-pan.
Sauté the aromatics: Heat olive oil in a large skillet over medium. Add onion and bell pepper.
Cook 4–5 minutes until softened. Stir in jalapeño (if using) and garlic; cook 30–60 seconds until fragrant.
Brown the turkey: Add ground turkey, breaking it up with a spatula. Season with salt and pepper.
Cook 6–8 minutes until no longer pink and lightly browned in spots.
Build the sauce: Stir in tomato paste, chili powder, cumin, smoked paprika, and oregano. Cook 1 minute to bloom the spices. Add drained Rotel and chicken broth.
Simmer 3–4 minutes until slightly thickened.
Fold in the grains: Stir in the cooked rice or quinoa until evenly coated. Taste and adjust seasoning. A squeeze of lime brightens the flavors nicely.
Assemble: If using a baking dish, transfer the mixture.
Smooth it into an even layer. Sprinkle shredded pepper jack over the top in an even blanket.
Bake: Place in the oven for 12–15 minutes, until the cheese is fully melted and the edges are bubbling. For a golden top, broil 1–2 minutes, watching closely.
Finish and serve: Let rest 5 minutes.
Top with chopped cilantro or green onions. Serve with lime wedges and a dollop of sour cream or Greek yogurt if you like.