Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
   1      pound         cheese tortellini
   1 1/2  cups          pesto
   3      cups          cooked chicken -- cut in pieces
     1/3  cup           minced fresh parsley
     1/3  cup           snipped chives
   1      small         onion -- sliced thin
   8      ounces        plain yogurt
     1/4  cup           olive oil -- if needed
                        ***PESTO***
   4      cups          coarsely chopped fresh basil
   1      cup           pine nuts
     1/2  cup           olive oil
   1      cup           freshly grated parmesan cheese
     1/2  stick         unsalted butter -- softened, cut in
                        -- bits
   2      cloves        garlic -- crushed

Preparation:

To make the pesto: Puree all the ingredients for pesto in wor kbowl of food processor or in a blender, working in batches. Transfer to a small bowl and place a piece of plastic wrap directly on surface to prevent discoloring. (Pesto may be made in advance and kept covered and chilled. Will keep about 2 weeks). Cook the tortellini in a kettle of boiling, salted water until al dente. Drain well and refresh under cold water. In a large bowl toss together the tortellini and pesto. Cover and refrigerate for at least 4 hours (or overnight). Add the remaining ingredients, except oil. Combine well and add oil only if salad seems dry. Season with salt and pepper to taste.