Preheat oven to 375°F

In large bowl, combine ground beef, onions, bread crumbs, beaten egg, BBQ sauce, taco seasoning, and 1/2 tspn salt. Mix thoroughly, then gently press into the bottom of a 9-inch square baking pan. Bake for 20-25 minutes or until cooled through. Carefully pour off drippings.

Meanwhile, microwave potatoes according to package directions. In a medium bowl mash cooked potatoes with milk and butter. Stir in bacon and fried onions. Season to taste with salt and pepper. Spread over meatloaf to the edges of the pan; sprinkle with cheese. Return to oven for 15 minutes. Slice and serve.