We have a couple of Jamie Oliver's themed cookbooks (Italy, USA), and although the recipes are good they are not always that well suited to spontaneous cooking. Jamie at Home is much better, and we've used it more frequently.
One of our favourite spring treats is his rhubarb bellini -- very quick, and ridiculously tasty. No need to splurge on the bubbles, either: cheap prosecco or cava both work well.
Ingredients:
Rhubarb
Sugar
Bubbly
More from the man himself, or one of his minions, here.