Preheat oven to 425 degrees F. Line a 15x10x1-inch baking pan with foil. Trim stems and remove any wilted outer leaves from Brussels sprouts; wash. Halve Brussels sprouts; spread in a single layer in prepared baking pan. Drizzle oil over Brussels sprouts. Roast for 20 to 25 minutes or until crisp-tender, stirring once or twice.
Meanwhile, for sauce, in a large nonstick skillet melt butter over medium heat. Add garlic; cook for 30 seconds. Add balsamic vinegar, dates, salt, and pepper. Cook for 5 to 7 minutes or until sauce is thickened and reduced to about ¼ cup.
Add roasted Brussels sprouts to the sauce in skillet; stir to coat.
