Preheat the oven to 500 degrees. Heat a large oven proof skillet over high heat. Add the clams, onions, curry powder and butter. Toss until onions start to brown. Top the clams with all the remaining ingredients except the heavy cream and scallions. Bring to a boil, transfer to the oven and roast for 9 minutes, turn the clams and roast for about 9 to 10 minutes longer, until they pop open. Transfer the clams and most of the solids to 2 serving bowls. On the stovetop, over a medium high flame, add the cream to the liquid left in the skillet. Stir constantly until the cream is completely incorporated. Divide the liquid between the 2 bowls, top with scallions and serve immediately with a generous spoonful of rice per bowl.
Note: Instead of rice, you may serve the clams with mashed potatoes or creamy polenta. If you would like to serve the clams as an appetizer, divide among 4 bowls and omit the rice.