Cut baguette into ⅜" slices and place on a baking sheet.
Brush the top sides evenly with olive oil.
Bake for approximately 15 minutes or until lightly toasted. Set aside to cool.
Cut the stem and root ends off the onions.
Cut the onions in half from stem to root, peel off papery layers
With the flat side down, slice the onions stem to root again, into ⅛" thickness.
Using an extra-large, heavy-bottomed pan, melt the butter plus one tablespoon of olive oil over medium heat.
Once hot, add onions, and a pinch of kosher salt. Stir.
Continue cooking and stirring until the onions soften and brown, and fond forms on the bottom of the pan.
Add a small amount of white wine or warm water to the pan, scraping to release the fond.
Continue until the onions are a deep brown, repeating the deglazing process as necessary.
Remove from heat.
Store onions in an airtight container in the fridge and warm slightly before serving.
Assemble as follows to create two flavor variations:
Start with a toasted baguette, and spread with a generous dollop of goat cheese. Top with a mound of warm caramelized onions and a sprinkle of capers.
Start with a toasted baguette, and spread with a dollop of garlic and herb soft cheese. Top with warm caramelized onions and a spoonful of red pepper jelly.
Notes
Fond is French for base and refers to the delicious caramelized drippings and browned bits of meat and vegetables that stick to the bottom of a pan during searing, sautéing, or roasting. Fond is a terrific source of flavor and is generally deglazed (removed and incorporated into the dish,) with a liquid, such as water, chicken/beef/vegetable stock, or wine that enhances the main ingredients being cooked.