In a small, dry skillet toast the pine nuts over medium heat, stirring constantly, until fragrant. Transfer to a dish to cool.
Peel, trim, and finely dice the onion. Peel, trim, and mince the garlic.
In a large skillet, cook the onion in the olive oil over low heat, stirring, until translucent. Add the garlic, saffron, and white wine and cook, stirring, for a few more minutes to blend. Add the chicken broth, bring it to a boil, and cook for 5 minutes. Stir in the cream and cook until slightly thickened, about 3 minutes. Turn off the heat and let the sauce cool to
room temperature
Cut the florets off the head of broccoli and trim into bite-sized pieces.
Cut the cauliflower into bite-sized florets.
In a large saucepan, bring the water to a boil with the salt. Add the broccoli and cauliflower florets and blanch for about 3 minutes. Drain in a colander and rinse thoroughly under cold water; let drain in the sink.
Bring a large pot of salted water to a boil. Add the pasta, stir to separate, and cook over high heat for about 8 minutes, until al dente. (Or follow the cooking directions on the package.) Drain in a colander. To prevent the pasta from sticking together, spread it out on a large baking sheet or platter and let it cool, about 15 minutes. Cover and hold at room temperature for up to 3 hours.
Put the pasta in a large bowl, add the cauliflower and broccoli florets, and toss lightly. Stir in the saffron sauce, add the toasted pine nuts and pepper, and toss to combine. Serve within 1 hour.