This dip is delicious right away, but better if you leave it in the fridge overnight to give the flavors time to blend.
Slice the top off a bulb of garlic and drizzle on a little olive oil. Wrap the bulb loosely in tin foil and bake at 400 degrees for about an hour, until garlic is soft and top is slightly caramelized. Let cool.
Mix cream cheese with 1/4 to 1/2 cup buttermilk or skim milk, until it is smooth and thinned out enough for dipping. Squeeze garlic bulb into cream cheese and mix thoroughly. Stir in spices and scallions. Serve at room temperature with pita chips, carrots slices, and celery.
If you don't have time to roast your garlic, you can substitute 1 teaspoon roasted garlic powder. For a sharper garlic flavor, use fresh minced garlic. Chopped sun-dried tomatoes are also good in this dip.