The osteria is all dark hues, and its sommeliers wear Windsor ties; the adjoining pizzeria is bright and relaxed, with cooks behind the counter forming delectable pies. The restaurants are linked by the shared philosophy of Nancy Silverton and Mario Batali, the double threat behind this always-crowded venture. Flavors build in increments toward full-throated generosity: Lemon zest and hazelnuts ramp up the power of the sheep's milk ricotta at the osteria's mozzarella bar; the radicchio and the escarole magnify the meaty tones of the guanciale on one of the more popular pies.