Preheat oven to 350°. Whirl red peppers, tomatoes, and 1/2 tsp. salt together in a food processor until puréed. Pour into a wide 4-qt. shallow baking dish or 6 shallow 1-cup baking dishes. Set aside.
Set poblanos over flames on a gas range (or set on a baking sheet and broil). Cook, turning often, until starting to turn black in spots, 8 minutes total. Let cool.
Slit poblanos and remove seeds as shown at left.
Heat oil in a large frying pan over medium-high heat. Add onion, garlic, jalapeño, and coriander. Cook until softened, 4 minutes. Add shrimp and remaining 1 tsp. salt. Cook until shrimp starts to turn pink, 2 minutes. Transfer to a bowl.
Stir cream and jack cheeses into shrimp mixture. Spoon into poblanos, dividing evenly. Set chiles in dish with sauce. Bake until filling is oozing and hot, 40 minutes. Top with queso fresco and cilantro.
*Find at well-stocked grocery stores and Mexican markets.