The day before the party, make the base for the pasta seafood topping. Melt the butter in a skillet. When the foaming subsides, add the shallots, carrot and celery. Cover and cook over low heat for 10 to 15 minutes or until very tender and almost dissolved in butter. (If at any time the vegetables begin to stick to the skillet, add a tablespoonful of water or wine.) Uncover the skillet, add the saffron and white wine and boil over high heat until almost all of the wine has evaporated. Add the fish stock and simmer for 5 minutes. Season to taste with salt and pepper (do in advance up to this point.) Boil the pasta until al dente. While this is cooking, add the heavy cream to the skillet and simmer again until the sauce is slightly thickened. Add the shrimp and scallops and simmer just until the seafood is cooked through. Add the tomatoes and simmer just for a minute to warm them through without really cooking them. Adjust the seasoning. Drain the pasta and portion it out among 6 warm pasta bowls. Ladle the saffron seafood sauce over the top and garnish with warm microwaved peas.