Add sliced Sunions and cook until reduced and caramelized -- approximately 25 minutes, stirring occasionally. Do not let them burn. Set aside.
Preheat oven to 400°. Cut garlic bulb in half and place in small baking dish. Drizzle with olive oil and bake for 50-60 minutes or until slightly browned and fragrant.
Remove garlic from oven and squeeze out the cloves into a dish.
In a blender or food processor, combine the garbanzo beans, garlic, 1/2 of the olive oil, tahini, 1/2 of the thyme, cumin and lemon juice. Blend until smooth. Add water or more olive oil, as needed, to smooth out the hummus. Add salt and pepper to taste.
Transfer hummus to bowl. Drizzle remaining olive oil and caramelized onions on top. Sprinkle with remaining thyme and salt.
Serve with toasted baguette slices, pita or crackers.