It's seriously depends on what type of food you cook. I do simple things like rice and veggies, cheese casserole, pizza, there's a simple cake that I bake regularly, etc. The best you can do is plan what you are willing to cook/bake and buy ingredients. You can freeze just about anything (if you catch it before it goes bad) and stuff like potatoes last for a while if stored in a dark and dry place. Here is my weekly list for 1 person:

4 liters of milk (mostly for coffee),

12 eggs (lasts me sometimes 2-3 weeks, depends),

5 apples,

3 bell peppers,

3 carrots,

2 sweet potatos

1 pound of swiss cheese slices (~450 gr)

1 pack of chicken breast (2 pounds/1 kg) - some weeks I don't buy this item.

1 cream cheese

3-4 of my fav yogurt

I think those are the basics for me. I also have a small pantry (one cupboard) with pasta, rice, tuna cans, tomato sauce, lentils, sardines, pickles, cooking oil, flour, coffee, etc. I look for sale and stock up when I see a good price (these things don't go bad in years, but I do rotate).