Beat egg and milk together.  Stir in cheese, oats, onion and salt.  Add beef and mix well.  Shape into 8 loaves; place in greased 13 x 9 x 2" dish.  Combine ketchup, brown sugar and mustard; spoon over loaves.  Bake, uncovered, at 350 degrees for 35 - 45 minutes.

I have used different kinds of cheese and it still tastes good.

I have also made them into meatballs.  I cook the meatballs about 1/2 hour and then put them in slow cooker, then add sauce.  Yum!