Bring chicken stock to a low simmer in a small saucepan and add saffron. Stir and let steep for at least 15 minutes.
Heat olive oil in a small saucepan and add shallot. Sauté a few minutes, without browning.
Add wine and simmer for another few minutes until the wine is reduced to a glaze. Stir in tomato paste.
Add steeped stock and saffron; gently simmer for 20 minutes over medium/low heat.
Add cream and again, simmer for about 30 minutes (or a little more), until sauce is reduced to about ¾ cup to 1 cup. It will be thick enough to coat the back of a spoon.
Meanwhile cook pasta. Drain when el dente. Toss with ½ TBSP butter so that the pasta doesn’t stick, especially if plating individually.
Add salt and cayenne (if using) to the saffron cream mixture and toss with the pasta, or plate individually.
We toss the pasta and sauce for a family style platter. If plating individually, place pasta in the dish. Drizzle with Creamy Saffron Sauce and add garnish: Prawns and Asparagus.