Preheat oven to 350°. Slice ¼ inch off top of each garlic head. Place garlic, cut side up, on foil and drizzle with 2 teaspoons oil. Wrap garlic in foil to seal. Place directly on oven rack and roast 1 hour. When cool enough to handle, squeeze out garlic into small bowl. You should have about ½ cup.
In food processor
with knife blade attached, add sour cream,
mayonnaise, cheese, lemon juice, thyme, salt
and garlic. Process 20 seconds or until mixture
is smooth, scraping bowl occasionally with
rubber spatula. Transfer to serving bowl; cover
and refrigerate at least 2 hours or up to 3 days.
To serve, drizzle with remaining oil. Serve
with crackers or toasted baguette slices.