Hardest thing, caramelized onions, use a mandolin to get them thin, low to med and slow, more than 40 min, stir a bit, but it takes time to get that deep golden brown without burning, but that's the flavor! You can use sour cream if you don't like yogurt but it does change the flavor, also you can add some good mayonnaise. I have also made it with sour cream and goat cheese! The onions are the key!

2 tbsp. unsalted butter 3 large onions, thinly sliced Kosher salt and pepper 1 tbsp. fresh thyme leaves 1/4 c. dry sherry wine 8 oz. crème fraiche 1/2 c. full-fat Greek yogurt 1 tbsp. grated lemon zest 1/4 c. chopped fresh chives

Melt butter in large skillet on medium-low. Add onions, season with 1/2 tsp salt and 1/4 tsp pepper, and cook, covered, stirring occasionally, until tender, 8 to 10 minutes.
Increase heat to below medium and cook, stirring frequently, until deep golden brown, 30 to 40 minutes. (Add 1 to 2 Tbsp water if onions stick or pan browns). Stir in thyme and cook 1 minute. Stir in sherry and simmer until evaporated. Let cool.
Mix in crème fraiche, yogurt, and lemon zest until smooth. Fold in all but 1 Tbsp chives. Let stand 30 minutes or refrigerate to let flavors meld before serving.
Sprinkle with remaining chives and serve with toasted baguette.