• Use an unlined cast-iron casserole or heavy metal roasting pan. Do not line the pan with parchment paper. Parchment creates a barrier between the Brussels sprouts and the hot pan, reducing the direct contact needed to develop deeply browned, crisp edges.
• Lay the whole bacon slices in the cold pan and place the pan in a cold oven. Set the oven to 425°F. Starting the bacon in a cold oven allows the fat to render gradually before the bacon becomes crisp. Cook for approximately 15 to 20 minutes, or until crisp. Transfer the bacon to a plate, leaving the rendered fat in the pan.
• While the bacon cooks, melt the butter in a small saucepan over medium-low heat. Add the shallot and cook for 2 to 3 minutes, until softened.
• Add the apple cider, brown sugar, Dijon mustard, apple cider vinegar, thyme, and coriander. Bring to a gentle boil, then reduce the heat and simmer until the cider mixture has reduced by about half and lightly coats a spoon. Remove the thyme sprigs and take the glaze off the heat.
• Carefully add the Brussels sprouts to the hot bacon drippings. Season with the kosher salt and freshly cracked pepper, then toss until lightly coated. If the bacon did not render enough fat to coat the sprouts, add a small amount of avocado oil.
• Arrange the Brussels sprouts cut-side down directly against the hot pan. Roast at 425°F for 20 to 25 minutes, until deeply browned and nearly tender.
• Pour the apple cider glaze over the roasted Brussels sprouts and toss to coat. Return the pan to the oven for approximately 5 minutes, until the glaze clings to the sprouts and begins to caramelize.
• Chop or crumble the reserved bacon. Remove the Brussels sprouts from the oven, toss with the crisp bacon, and serve warm.

Notes

• The cider mixture does not need to become thick or syrupy on the stovetop. Reduce it by about half; it will continue to thicken and caramelize during its final few minutes in the oven.
• I use my freshly cracked mixed pepper blend, but freshly cracked black pepper also works well.
• Because bacon varies in saltiness, season the Brussels sprouts lightly before roasting. Taste after adding the bacon and adjust if needed.