Hi Juanita,
Oh those fond memories....although I never ate in a cafeteria in elementary school....I did work for a large school district in Los Angeles for 5 years, and was secretary to the Director of Food Services....we had wonderful cooks at all of our 17 schools in our district, and one of my favorites lunches at the school cafeterias was "Salisbury Steak", which is what I believe you were describing. I used to have that recipe, but when I moved to Georgia 10 years ago, I somehow lost some good recipes...however, I can tell you what that secret ingredient was to make those salisbury steaks so good....COTTAGE CHEESE...I was shocked too... but what I would do is use your favorite recipe, or one that I'll type below from another cookbook just as sort of a base, and you can substitute the buttermilk for cottage cheese,....as for the gravy....I make gravy the way Elly described "roux" which you use equal parts fat/flour, stir until browned, add liquid to desired consistency, (the liquid is milk, if for gravy over bisquits), and water if to smother meat or chicken or whatever. You can also add a can of soup ie; cream of mushroom, cream of onion, potato, whatever...after your roux has browned properly, I would dilute the canned soup, of course. Below is a recipe from a old Sealtest cookbook circa - 1963.
It sounds different....and good..

WHIPPED HAMBURGER PATTIES

l lb. ground beef
1-1/2 tsp salt
1/8 tsp. pepper
l medium onion, grated
l cup Sealtest buttermilk
1/2-3/4 cups fine dry breadcrumbs

Combine beef, salt, pepper and onion in large bowl. Whip mixture with electric beater, or large spoon, until light. Add buttermilk gradually, beating constantly. Mix in bread crumbs adding just enough so that mixture can be shaped into patties. Shape into patties and cook in skillet until browned on both sides. Makes 6 generous servings.

P.S. Another suggestion for "ground beef Night"....how about tamale pie????