Rinse each Poussin, pat dry, and cut off and reserve the wings at the second joint. Gently loosen the skin from the breast meat and smear about 2 tsp. of the soft butter under the skin of each bird. Slide in a few sprigs of herbs. Put a few more herb sprigs along with 2 garlic cloves, into each cavity. Rub the rest of the butter on the outside of each poussin, and then season inside and out with the salt and pepper. If you like, tie the ends of the legs together for a neater presentation.
Heat the oven to 400F in two large ovenproof saute pans or medium roasting pans, toss te reserved wing tips, carrots, potatoes, and any remaining herbs. Arrange the Poussin, breast side down, on top of the vegetables and wing tips. They can fit snugly, but they shouldn't be squeezed together. Sprinkle with salt and pepper and then pour in the broth and lemon juice. Cover the pan with a lid or foil and cook in the hot oven for about 15 minutes. Remove the lid, turn the Poussin so they are breast side up and there's room for air to circulate and brown the skin. Baste them with a little pan juice and continue roasting (uncovered), basting a few more times, until they are golden brown and the juices run clear from their cavaties or from their thighs when pricked with a knife (an instant-read thermometer should read 170F). This should take about another 30-35 minutes.
About 10 minutes before you think the Poussin will be done, distribute the asparagus in the roasting pans to cook it. If you're not sure about the timing, or if your pan is too full, simply boil the asparagus seperately for about 5 minutes in salted water.
Remove the Poussin and vegetables from the pans and keep them warm. Strain the pan juices, skim of as much of fat as possible, and taste. If they're a little thin, boil them for a few minutes to concentrate the flavour; season with salt and pepper. If the sauce tastes too lemony, whisk 1 or 2 tbsp cold butter.
To serve, put one Poussin on each plate and arrange the vegetables around it. Pour over a few spoonfuls of the sauce and garnish with shreds of lemon zest and some fresh herbs.View more Chicken recipes...