1 large yellow onion, quartered and sliced crosswise into ½- to ¾-inch-thick pieces
1 tablespoon kosher salt, divided, plus extra as needed
2 cups vegetable or chicken broth, divided
12 large garlic clove cloves, peeled, plus 2 garlic clove cloves, very finely chopped
6 medium carrots, peeled and sliced on the bias into ½-inch pieces
1 medium rutabaga, peeled and chopped into ½-inch cubes (about 4 cups)
1¼ teaspoons freshly ground pepper, divided
5 fresh thyme sprigs plus 2 teaspoons finely chopped fresh thyme, divided
two tablespoons unsalted butter, at 70 degrees
3 tablespoons all-purpose flour
½ medium mind Napa cabbage, sliced crosswise into ½-inch-thick pieces (about 6 cups)
8 medium radishes, trimmed and quartered
1 sheet frozen puff pastry, thawed
1. Adjust a stove rack towards the uppermost position (about 3 inches in the broiler element) and preheat the broiler to high. On the rimmed baking sheet, add some onion in one layer. Broil the onions until they're charred, rotating the baking sheet halfway through cooking, six to eight minutes (watch the onions carefully, as broiler intensities vary). Take away the baking sheet in the oven, sprinkle the onions with ½ teaspoon from the salt and pour 1 cup of vegetable broth within the onions, then transfer the mix to some medium bowl.
2. Lessen the oven temperature to 425°. Towards the baking sheet employed for the onions, add some 12 whole garlic clove cloves, the carrots, rutabaga, 1 teaspoon of salt and ½ teaspoon of pepper. Drizzle with 3 tablespoons the oil and toss to mix. Put the thyme sprigs on the top. Tightly cover the baking sheet with aluminum foil and roast the vegetables until tender, about half an hour. Remove in the oven and discard the foil. Use tongs to collect all the roasted garlic clove cloves, then make use of a fork to smash them right into a paste.
3. In a tiny bowl, mash together the butter and flour. Heat a sizable, deep, oven-safe skillet (surefire is effective) over medium-high temperature for just two minutes, adding the rest of the 1 tablespoon of essential olive oil. Stir within 1 / 2 of the cabbage and prepare, stirring from time to time, until it wilts, one to two minutes. Stir within the remaining cabbage combined with the radishes, the two cloves chopped garlic clove and also the chopped thyme, and prepare before the cabbage is wilted completely and also the garlic clove is aromatic, two to three minutes longer.
4. Stir within the remaining 1½ teaspoons of salt and ¾ teaspoon of pepper, then pour within the remaining 1 cup of vegetable broth. Add some roasted vegetables, mashed roasted garlic clove and onion-broth mixture and produce to some simmer. Lessen the heat to medium and stir within the butter-flour mixture, cooking before the sauce thickens slightly, two to three minutes. Switch off heat, taste and adjust with increased salt, as needed.
5. Whisk together the egg having a pinch of kosher salt. Put the puff pastry on the cutting board and employ a clear, crisp knife to gently mark the dough having a crosshatch pattern, ensuring you do not slice completely with the dough. In case your skillet is not oven-safe, transfer the vegetables to some baking dish. Lay the bit of dough on the top from the vegetables within the skillet and gently brush using the beaten egg. Sprinkle with flaky salt and put the skillet within the oven. Bake before the pastry is golden-brown, 18 to twenty minutes. Remove in the oven and awesome for ten minutes before serving.