French Onion and Chestnut Soup | Savory au Gratin

Peel the onions, halve them, and cut them into thin strips. Roughly chop the pre-cooked chestnuts, setting aside a few nice halves for garnish. Wash the fresh thyme and pat dry.

In a heavy Dutch oven, melt the unsalted butter over medium heat. Add the onion strips and sweat them gently, stirring occasionally, for about 15 to 20 minutes until they achieve a golden-brown, aromatic caramelization.

Add the chopped chestnuts and half of the thyme leaves to the caramelized onions in the pot and sauté for 2 minutes. Then deglaze with the white wine, loosening the browned bits from the bottom of the pot. Let the wine reduce by about half.