Here's how I do hamburger. I buy in bulk then cook it all at once, in two or three batches, adding salt and onions. Then I rinse it in a strainer with hot water, pouring some dish soap in the corner of the sink to handle the grease. Then I put about 3-4 ounces each in folding-type sandwich baggies, squeezing out excess air and twisting to close. I put all the baggies inside a gallon ziplock bag and label with the date, then freeze. When needed, I pull out one or two baggies and microwave on high for one minute to thaw. Then I use for spaghetti, tacos, hamburger helper, or other casseroles. It cuts out a ton of time and labor!
I also do the same with a chicken casserole that I make. I will tripple the ingredients, then divide and put in freezer bags, freeze flad on a cookie sheet. When ready to use, pull out of the freezer, takes about 30" to thaw, then place in a dish and bake.Makes meal prep really fast when you're in a hurry.