Until quite recently, it was difficult or impossible to raise chicks in winter, so the term "spring chicken" referred to a small, tender, early season bird. (Now that you can buy any size chicken at any time of year, the term is more commonly applied negatively to a not-so-young person.)
Chicken in spring though, is another matter. In a season when grilling is not yet imperative and there are small, tender, early season vegetables -- carrots, peas, onions, potatoes, maybe a turnip or two -- to pair with it, this celebrates the wonderful transition from winter to summer.
The inspiration is the old chicken in a pot, in which you brown a whole chicken and then finish it, covered, with vegetables and liquid, creating a delicious broth that is a perfect setup for rice, bread, or buttered noodles. The liquid you use can be water, but if you've got homemade chicken stock -- or something close, I'll get to that in a moment -- so much the better. Use chicken stock finished with a bit of cream and you have a dish of unsurpassed luxury.
I'll admit that it takes some patience (though there is a shortcut), and of course good ingredients. The chicken is of primary importance, so if you can find something of better-than-mass-produced quality that's a good start. The vegetables are a little easier, because this time of year it's not much of a challenge to find really fresh carrots, peas (or snow peas, just as good), new potatoes, tiny turnips.
The stock is another question. I've long been an advocate of water as a braising liquid, for two reasons: One, I think packaged stock, whether canned or boxed, is actually a negative presence (and if you taste it straight you'll probably agree). And two, homemade chicken stock, though not difficult to make, is undeniably a chore, and so good that almost as soon as you make it ... you use it up. So, unless you're energetic and lucky enough to have stock around, water is a good starting place.
There is, however, a compromise. Take that water, combine it with the tips of the chicken wings, the neck that came with the chicken, a carrot, an onion, maybe a stalk of celery, whatever - and simmer that, just for 15 minutes. You'll have improved water, something akin to thin broth. But even if you stay with plain water, the chicken and vegetables will flavor it beautifully.
The most labor-intensive, difficult part of the whole cooking process is browning the chicken. If you choose to do so, your time will be well-rewarded: The dish will have deeper flavor and better color and texture -- it'll just be better. However -- and I do this myself when pressed for time -- you can skip it entirely. The bird will be paler, and the flavor perhaps a touch less complex, but the dish will still be gorgeous.
And chicken in a pot need not be prepared in this classic way: Swap out some of the vegetables for lentils, change the seasonings from subtle to spicy, and you have an Indian-style stew that will heighten anyone's spring.