For the Pork Loin:
In a small bowl, whisk together the garlic, olive oil, bay leaf and chives. Liberally season with salt and pepper, then rub the loin all over with the garlic mixture and refrigerate for 2 hours or up to overnight.
Preheat the oven to 425°F.
Remove the loin from the refrigerator and let it come to room temperature. Heat a large sauté pan over medium-high heat, and then sear the loin on all sides. Transfer it to a roasting pan and roast for 20 minutes, or until an instant-read thermometer registers 145°F.
Remove the loin from the oven and transfer to a cutting board. Tent with aluminum foil and let it rest for about 10 minutes.
Heat the drippings in the roasting pan over medium-high heat. Add the shallots and cook until they begin to soften. Add the wine and bring to a boil, then reduce the heat to maintain a simmer. Cook until the sauce has reduced by about half and thickened.
Remove the sauce from the heat and whisk in the cold butter, a cube at a time. Cut the pork into 1/2–inch slices, dress each portion with the sauce and serve.
For the Brussels Sprouts:
Fill a large bowl with half ice and half cold water. Bring a large pot of at least 6 cups water to boil over high heat. Salt the water heavily and add the Brussels sprouts. Boil the sprouts for 3 minutes, then transfer to the ice water bath. When they are cool, but the Brussels sprouts in half lengthwise.
In a large skillet over medium-high heat, heat the oil. Add the Brussels sprouts and sear, cut-side down, for 3-5 minutes. They should just begin to char, but not be burnt; watch them carefully. (Depending on the size of the skillet, you may need to work in batches.
Transfer the Brussels sprouts to a clean bowl. Add the butter and maple syrup to the pan and stir while the butter melts. As soon as the butter has melted, return the Brussels sprouts to the pan and toss to coat.
Transfer the Brussels sprouts to a serving dish and drizzle any syrup left in the pan over them. Squeeze the lemon over the top and serve warm.
For the Mashed Potatoes:
In a large pot, cover the potatoes with cold water and add the salt. Bring to a boil over medium-high heat and cook until the potatoes are fork-tender, about 15 minutes. Drain the potatoes in a colander.
In a medium saucepan over medium-high heat, combine the half-and-half, butter and white pepper. Heat until the butter has melted, and then whisk in the buttermilk.
Mash the potatoes in a large serving bowl with a masher. Add the hot liquid mixture, season with salt and black pepper, and stir thoroughly to combine. Mix in the chives and serve warm.