Why It Works Blanching and shocking the vegetables sets their color and delivers bright flavor and crisp texture. Gently infusing butter with whole garlic adds savory depth without a harsh minced-garlic bite. Crème fraîche and lemon keep the sauce creamy while letting spring vegetables stay bright. I find it very hard to imagine that prior to 1975, nobody in the history of the universe had thought to combine fresh spring vegetables and pasta in a creamy sauce, but, if  we are to believe Sirio Maccioni , chef of New York's famed Le Cirque, it's the truth. At least, nobody famous enough to take a good idea and turn it into an international sensation. Sirio put it on the menu, and pasta primavera—"spring pasta"—quickly became part of our cultural lexicon. Since then, pasta primavera has become a staple menu item across the spectrum of restaurants, from fancy places using handmade pasta and seasonal spring vegetables to chains that serve it year-round alongside bottomless baskets of breadsticks.…