PREHEAT OVER TO 400F. Combine the first 5 ingredients in a bowl and set aside. Cut 5-or-6 long slits in the eggplant (fewer if you''re using Japanese eggplants) and place a slice of garlic into each slit.
Wrap the eggplant, together with the bay leaf and thyme branches, tightly in foil and bake until completely soft all over--45 minutes-to-1 1/2 hours, depending on the size of the eggplant.
If you''re using the large eggplant, turn it over after 45 minutes and continue baking until soft to the touch and tender at the stem end.
When done, remove eggplant from the oven, open the package and let sit for 5 minutes or so. Discard any liquid. When the eggplant is cool enough to handle, scrape the flesh away from the skin, put it into a food processor and add the yogurt mixture and the olive oil.
Process until smooth, but leave a little texture. Stir in the lemon juice or vinegar to taste and season with salt. Turn the puree into a serving bowl and season with pepper and fresh herbs, such as thyme leaves and blossoms, marjoram or oregano.
If those herbs aren''t available, use some chopped parsley or scallions.
Serve the spread at room temperature with crackers, pita bread or bread toasted and brushed with olive oil.