Preheat the broiler. Line a broiler pan with foil and preheat 5 minutes.
Meanwhile, brush the carrots and onion with 1 tablespoon olive oil and season with salt and pepper. Brush the fish with the remaining 2 tablespoons olive oil, season with salt and pepper and sprinkle with the paprika; brush to coat the fish evenly with paprika.
Carefully remove the pan from the oven, place the fish in the center and scatter the onion and carrots around. Broil until the fish is golden and just cooked through, 8 to 10 minutes.
Meanwhile, microwave the peas in a bowl with 1/4 cup water until just tender, about 4 minutes. Transfer the peas and liquid to a food processor and pulse with the ricotta, butter and a pinch of salt to make a slightly chunky puree. Divide the puree among plates and top with the fish, carrots, onion and pan juices.