1/2tspdried thyme (crush with your fingers as you add it)
1tspfresh cracked black pepper
Peel the onions. I chop one of them. I halve the next, and thinly slice. I quarter the last one, and thinly slice. This gives me a nice variety of texture in the finished dip and avoids the 'stringly onion' syndrome that can happen with classic onion dip :)
Melt the butter and oil over medium heat in a large Dutch oven and add the onions. Cook them until they start to soften, stirring often. About 5 minutes.
Add the salt and brown sugar to the pan and stir well.
Now you'll continue to cook the onions, uncovered, over medium heat, for as long as it takes to caramelize them: this will be about an hour. You'll want to stir every so often. The key here is that you don't want them to brown right away, you want them to soften and lose their moisture. The heat should be high enough to cook them, but not so high that they're browning on the bottom of the pan (this will happen at the very end of the caramelization process.) The onions will release moisture first, then SLOWLY turn from golden to brown. Your nose will tell you when it's close. (See tips in the post for more details.)
When the onions have reduced way down and have turnd a nice deep golden brown, you can deglaze the pan with the cognac. Scrape up any browned bits from the bottom of the pan at this point and remove from the heat to cool.
Preheat the oven to 375F
Put the mayo, sour cream, cheeses, thyme, garlic, salt and pepper into a bowl and blend. Fold in the cooled onions.
Spread into a gratin dish, cast iron skillet, or other oven safe baking dish.
Bake for about 25-30 minutes, or until the dip is bubbling and golden on top. The baking time will vary depending on the size of your dish.
Serve hot with thin slices of baquette that have been toasted. Reheat, if necessary, in a low oven, or reheat smaller portions briefly in the microwave.
https://theviewfromgreatisland.com/baked-caramelized-onion-dip-recipe/ October 30, 2020