Bread Pudding with Caramelized Onions

Ingredients:

• 110g unsalted butter, plus extra for greasing
• 1 baguette 60 cm long.
• 2 large onions, thinly sliced ​​(about 1.3 kg),
• 1 tbsp fresh thyme leaves
• 1 cup dry white wine
• 1 beef bouillon cube, crumbled
• 1 cup heavy cream
• 1/4 cup chopped fresh chives
• 4 large eggs
• 6 cups grated Gruyere
• Special equipment: 6 ramekins, 240 ml each.

Preparation:

1. Preheat oven to 350°F (175°C). Grease six ramekins with butter and place on a rimmed baking sheet.
2. Cut six 1-cm-thick slices of baguette and place them on a baking sheet. Cut the remaining baguette into 1-cm cubes (you should have about 4.5 cups of bread cubes) and arrange them on the same baking sheet. Bake, tossing the cubes and turning the slices halfway through, until golden brown, about 15 minutes.
3. Meanwhile, melt the butter in a large skillet over medium-high heat. Add the onion, thyme, 1 teaspoon salt, and season generously with pepper. Cook, stirring occasionally, until the onion begins to soften, about 6 minutes. Reduce the heat to medium-low and cook, stirring occasionally, until the onion is very soft and caramelized, 35 to 40 minutes.
4. Add the wine, increase the heat to medium, bring to a boil, and simmer until the wine has evaporated, about 5 minutes. Add 2 cups of water and the bouillon cube and stir until the cube dissolves. Bring the broth to a simmer and simmer until it thickens slightly, about 5 minutes.
5. In a medium bowl, combine heavy cream, chives, eggs, and 1/2 teaspoon salt. Add 1/2 cup bread cubes to each ramekin, sprinkle each serving with 1/4 cup Gruyere, and top with 1/4 cup bread cubes. Pour the egg mixture over the top. Divide the onion mixture among the ramekins. Top each ramekin with a toasted slice of bread and sprinkle with 3/4 cup Gruyere.
6. Let stand at room temperature for 15 minutes to allow the bread to absorb the egg mixture. Bake on a baking sheet until the custard is set and the bread pudding is fluffy and golden, about 20 minutes. Let rest for 5 minutes and serve.