Over medium heat melt the butter and olive oil together in a dutch oven or soup pot. Cut the top and bottom off of the onion and peel the outer layer. Stand the onion up resting on one of the sides that were sliced and cut in half. Cut both sides into thin slices and repeat with the second onion.

Put the sliced onions in the melted butter and olive oil. Add the sugar and salt and stir in. Caramelize the onion, this should take a good ten minutes at least. The sugar will help it on but stir about every few minutes or so until it reaches a slightly brown color. You can turn up the heat slightly once the onions have fully sweat.

When the onions are caramelized to your desire, add the balsamic vinegar, fresh thyme and basil chiffonade. Chiffonade is a French knife cutting technique that helps when cutting delicate herbs such as basil. Take a few leaves of basil and lay them on top of each other. Take one end and roll it up. With smooth strokes, slice the roll of basil.

Add the beef broth and let it come to temperature.

Using the broiler, toast one side of the bread slices.

When the soup has heated, ladle into individual bowls. Put the bread on top with the toasted side down and place a slice of Havarti cheese on top. Melt under the broiler.

Top with basil chiffonade and a balsamic reduction.