If I had to shop every week for everything I eat in that week, I think I would go insane. Even in my perfect ideal world where I have lots of time to cook and plan meals in advance (a world I don’t currently inhabit, alas), I like being able to “shop” my pantry. It’s much easier to stock up on non-perishable items you use often when your supplies are getting low than it is to buy every item individually each time you need it.
I keep a magnetic notepad on the side of my refrigerator. When I notice I’m about to run out of coffee, oatmeal, rice, canned beans, mineral water, spices or whatnot, I write it down. Then on my weekly shopping trip, I buy those few items, plus enough fresh produce, milk and yogurt for the week (I add eggs when my hens aren’t laying). Very streamlined, which is what I need right now with my hectic life! My pantry is so well stocked that many week, the perishable items are all that’s on my list.
So what’s in the Perfect Pantry? That depends on you! These are some of my go-to items:

Pantry

Canned tuna and salmon
Grains (brown and basmati rices, wheat berries and farro, bulgur, quinoa, polenta)
Pasta (although I don’t eat it often)
Oatmeal and other multi-grain hot cereals
Canned beans (white, pinto, black and chickpeas)
Dry beans (for when I have the time and forethought to cook them)
Canned tomatoes (diced, sauce, paste, and sometimes whole and crushed)
Canned artichoke hearts
Jarred roasted red peppers
Organic tomato or tomato-red pepper soup
Almond milk (for smoothies)
Dried fruits (to use in oatmeal)
Assorted vinegars (red, white, champagne, cider, balsamic)
Extra virgin live oil (one for cooking, a nicer one for salads)
Spices

Refrigerator

Capers
Kalamata olives
Dijon and other good mustards
Walnut and hazelnut oils (for salads, NOT for cooking!)
Quality mayonnaise (which I don’t use often)
Plain Greek yogurt
Milk
A few cheeses (Parmesan, blue, feta)
Salad greens
Fruit for snacks
Lemons for flavoring water or using in vinaigrettes
Other seasonal produce
Peanut and almond butters
Trader Joe’s pumpkin and fig butters (I use a dab to flavor plain yogurt)

Freezer

Raw nuts (walnuts, almonds and pecans)
Sprouted grain bread, English muffiins and pita bread
Veggie burgers (I like Dr. Praegers)
Veggie sausage
Chicken breasts
Salmon fillets
Frozen berries (for smoothies)
Beef (we buy 1/4 of a steer every year from a local small farm)
Containers of leftover soups and stews

I didn’t mention any baking ingredients, because my focus here is being able to put together healthy meals, quickly and easily. I also didn’t mention every single thing, because my pantry is overstocked right now. I have items I rarely use because I’m too busy to cook from recipes right now. I also have way too many jars of assorted Patak’s curry pastes. I’ve broken what I feel is a cardinal rule: Don’t put things in your pantry that you won’t use in a reasonable timeframe. If you only make wild rice once or twice a year, just buy it when you actually need it. If you use brown rice weekly, you should keep a container of it handy. 
My problem is that I have a good-sized dedicated pantry off my kitchen…plus overflow area in the basement. Ahem. That said, I can always put a healthy meal together for myself and whomever is dining with me with a minimum of fuss. For example, this Mediterranean-inspired salad is a favorite:

Tuna and White Bean Salad

Drain and rinse one can of white beans. Put in bowl. Drain one can of tuna. Use a fork to flake it into the bowl. Toss in a few tablespoons of capers or quartered Kalamata olives. Add vinaigrette (or olive oil and vinegar) and salt and pepper to taste. Serve on bed of lettuce.
How easy is that? Very easy. You can easily ramp it up a bit by adding some walnut halves, cherry tomatoes, diced roasted red peppers. You can use lemon juice instead of vinegar. It’s delicious!
Grains and beans make a great base for salads (they pack really well for lunches). Here’s a concoction I threw together Monday night for Tuesday lunches:

Wheatberry, Chickpea and Chicken Salad

Put cooked wheatberries in bowl.* Drain one can chickpeas, add to bowl. Dice chicken breasts or thighs (we grilled extra on Sunday), put in bowl. Quarter some Kalamata olives, add to bowl. Sprinkle in some feta cheese (you don’t need much, because it’s so flavorful). Add vinaigrette or oil and vinegar, and toss to combine.
* I put 3/4 cup wheatberries (all I had left) with 3 cups water (1:4 ratio) into a small pot, covered, brought to a boil then reduced to a simmer. They took about 40 minutes, but I checked for doneness at 30 minutes by bite testing. When fully cooked, wheatberries will be chewy and firm, but not hard to chew. Drain when done.
I hate instant oatmeal packets with a passion. They are gummy, overly sweet…and it’s easy and quick to make my own:

Stovetop Oatmeal

Add 1/3 cup oatmeal (regular or thick) and 2/3 cups liquid (1:2 ratio) per person to a pot (smaller pot for fewer portions) over medium heat. Add a pinch of salt. I like to add vanilla extract and cinnamon, and sometimes a pinch of nutmeg. I don’t use sweeteners, so I often add some chopped ripe banana or some dried raisins or Craisins. 
Stir to combine as you add things, but you can mostly leave it alone until it starts to bubble. When it does, turn down the heat to a simmer, and start stirring. Sometimes I stir a little, sometimes a lot. I’m not sure that it matters! Just make sure it’s simmering instead of boiling and spewing. 
Cook until it has the consistency you like, and serve. I often top mine with some unsweetened shredded coconut and a few nuts or a small dollop of nut butter. Sometimes I do sweeten slightly…with Trader Joe’s pumpkin butter.