Cook bacon in a large skillet over medium, turning occasionally, until browned and crisp, about 10 minutes. Transfer to a plate lined with paper towels; reserve drippings in skillet.

Add shallots to hot drippings, and cook over medium, stirring often, until shallots are softened and start to brown, about 8 minutes. Add garlic, and cook, stirring often, 1 minute. Add vinegar, and cook until thick and syrupy, about 2 minutes. Remove from heat, and pour into a small microwavable bowl. Crumble bacon, and stir into shallot mixture. Cool to room temperature, cover, and chill until ready to use, up to 1 day ahead.

Preheat oven to 400°F. Toss Brussels sprouts with canola oil, 1 teaspoon of the salt, and 1⁄2 teaspoon of the pepper. Transfer to 2 aluminum foil-lined rimmed baking sheets. Roast Brussels sprouts in preheated oven until golden and tender, about 25 minutes, stirring halfway through baking. Set aside for up to 1 hour.

Combine breadcrumbs, melted butter, and remaining 1⁄2 teaspoon salt and 1⁄4 teaspoon pepper in a small bowl. Set aside.

Microwave bacon-shallot mixture on MEDIUM (50% power) until mixture can be stirred, about 30 seconds. Toss roasted Brussels sprouts with bacon-shallot mixture, and transfer to a lightly greased 13- x 9-inch baking dish. Sprinkle evenly with breadcrumb mixture, and bake at 400°F until heated through and breadcrumbs are golden brown, about 15 minutes. Let stand 10 minutes before serving.