-
1
Add butter and olive oil to a saucepan just large enough to hold the onions, over medium heat.
-
2
When butter melts, add the onions, stir to combine and then cover the pan.
-
3
Reduce the the heat to med-low and cook, stirring occasionally until onions have wilted and given up their juices (about 30 minutes).
-
4
When the onion have wilted, add the thyme and pepper; stir to combine and continue to cook, covered, stirring occasionally until the onions have darkened to a deep golden brown (about 30 more minutes).
-
5
If there are any juices still in the pan, just uncover and raise the heat to medium and cook, stirring constantly for 1-2 minutes until most of the juices have evaporated.
-
6
Remove the onions and place in a bowl.
-
7
Allow to cool to room temperature.
-
8
When the onions have cooled, add the grated cheese and stir to combine (this onion/cheese mixture can be prepared up to one day in advance and stored tightly covered in the refrigerator.
-
9
When ready to serve, preheat oven to 375F.
-
10
Arrange the baguette pieces on a cookie sheet and divide the cheese/onion mixture on top of the bread, gently smoothing the topping over the bread.
-
11
Bake for about 8 minutes, until the crostini are bubbling and golden brown.
-
12
Serve hot or warm.
