The filling

Slice the onions into narrow slivers. In a large heavy skillet, heat the oil and butter over medium heat until the butter melts. Add the onions and saute for 10 minutes moving the onions around frequently so that they cook evenly.

As the onions begin to brown, add the sugar and continue to saute for another two minutes. Remove from the heat and add the sherry. Mix the sherry in well and allow the onions to cool; they will absorb more of the sherry as they cool.

The bread

Slice the bread at a slight angle into 1/4 inch thick slices. Place these slices onto an ungreased cookie sheet. Bake at 425 degrees for 3 to 4 minutes or until the bread begins to crust up a little bit. Remove from the heat and place a tablespoon of the onion filling on top of each slice.

The finish

Sprinkle with a little grated parmesan cheese if you like and place them back into the oven for another 3 to 4 minutes until they are well warmed. Serve while still warm.