Preheat the oven to 400 degrees F. Divide the asparagus spears into 12 bundles. Carefully wrap 1 piece of bacon around each bundle, starting about 1/2 inch from the bottom of the tips. Secure the bacon-wrapped spears with a toothpick. Lay the bundles in a low-sided casserole dish. In a medium saucepan, combine the brown sugar, butter, soy sauce, garlic salt and pepper. Bring the mixture to a boil. Pour the hot sugar mixture over the asparagus bundles. Transfer the dish to the oven and roast until the spears have begun to wilt and the bacon looks fully cooked, about 25 minutes. Remove the toothpicks before serving.