Bake uncovered for 1 and 1/4 hours, or until the top is crusty and well-browned and a meat thermometer reads 145 degrees F. when inserted into the center of the loaf. Allow loaf to stand at room temperature for 10 to 15 minutes prior to cutting it into pieces.
Cut into pieces and transfer pieces to a large serving platter. Cover with heavy-duty aluminum foil while you make the gravy.
Meatloaf Gravy:
Place meatloaf drippings in a medium saucepan. Heat until gently simmering. Add butter. Combine water and cornstarch in a cup, using a fork to whisk them together. Slowly add the cornstarch mixture to the bubbling gravy and whisk in, stirring constantly, until thickened. Salt and pepper to taste. Serve over meatloaf and mashed potatoes.