Before making the sauce, sear your protein (steak, chicken, or pork) in a 12-inch skillet until well browned and desired internal doneness has been reached; transfer to a warm place to rest. Pour off all but 1 tablespoon remaining fat from the skillet.
Add butter and melt over medium-low heat. Add peppercorns and shallot and cook, stirring frequently, until shallot is softened, 3 to 5 minutes.
Add flour and cook, stirring constantly, until well combined, 2 minutes. Increase heat to medium and whisk in brandy, scraping the bottom of the pan to loosen the fond and cook for 1 minute, then pour in stock and whisk to combine. Add a sprig of thyme and bring to boil, then cook, whisking occasionally, until mixture reduces to 1½ cups, 12 to 15 minutes.
Whisk in cream and cook, whisking occasionally, until reduced to 2 cups, about 10 minutes. Discard thyme sprig, then season sauce with salt and pepper to taste. Serve with the reserved meat (if needed, you can quickly put the meat under a broiler or in a very hot oven just to warm it back up).
