Using a small sharp knife, carefully slit roasted chiles open along one side. Remove seeds, leaving stems attached. Set aside to fill later.
Prepare the Filling: Heat a large skillet over medium high heat. Add oil to pan and swirl to coat. Sprinkle shrimp with ¼ teaspoon salt. Add shrimp to pan; cook 3 minutes or until done. Remove from pan and reserve.
Add garlic to pan; saute 30 seconds, stirring constantly. Add flour and ground black pepper; cook 1 minute, stirring constantly. Slowly add crema Mexicana, stirring with a whisk. Stir in ½ cup milk; cook 1 minute, stirring constantly. Remove from heat let stand 2 minutes.
Add quesadilla cheese and ¼ teaspoon salt and stir until smooth and cheese melts. Place ⅓ cup of cheese mixture in a large bowl; reserve remaining cheese mixture.
Add cooked shrimp, roasted bell pepper, cilantro, and lime juice to the ⅓ cup cheese mixture; toss to coat.
To Serve: Stir remaining ¼ cup milk into reserved cheese mixture. Spoon 3 tablespoons of the cheese sauce onto each of four plates.
Stuff each poblano chile with 6 tablespoons shrimp mixture. Place 2 stuffed poblanos onto each plate with cheese mixture and garnish with crumbled queso fresco, some cilantro, and pomegranate seeds (optional).
