Chop onion into small pieces (about 1/2" x 1/4") and mix with mayonnaise and cheddar cheese. Put in small ovenproof casserole and bake at 350° until bubbling. Put chopped garlic in the olive oil. Spread baguette slices on cookie sheet and brush with garlic and olive oil mixture. Toast in oven until lightly browned. Top Baguette with the onion-cheese dip. Serve warm.
