In a bowl, combine 1/4 cup ketchup, egg, bread crumbs and onion powder.
Crumble beef over mixture and mix well.
On a large piece of waxed paper, pat beef mixture into a 10-in x 6-in rectangle. Spread remaining ketchup over meat to within 1/2 in. of long sides and 1-1/2 in. of short sides. Top with mustard and relish.
Place four chesses slices on top; set aside remaining cheese.
Roll up loaf, jelly-roll style, starting with a short side and pulling away waxed paper while rolling.
Seal seams and ends well. Place loaf, seam side down, in a greased 11-in. x 7-in. x 2-in. baking pan.
Bake at 350 degrees for 45 minutes or until meat is no longer pink and a meat thermometer reads 160 degrees. Cut the reserved cheese slices in half diagonally; place on top of loaf. Return to the oven for 5 minutes until cheese is melted. Let stand for 10 minutes before slicing.