Chocolate milk. No, it doesn't last, but I'm always hungry two hours later no matter what I eat. Chocolate milk is something I'm always in the mood for (I microwave the 12 ounces for 2 minutes if I want something hot), it starts me on my calcium for the day, it has protein, and it makes it easier for me to remember to swallow any pills that need swallowing.
It's semi-mustachian. I make it with milk and home-made chocolate syrup (1 cup sugar, 1 cup cocoa, 1 cup water, heated until the sugar dissolves).
On a work day, I have pretzels for a snack to hold me until lunch. These are not so mustachian--spelt pretzels (so they have some fiber) bought at a store. On a weekday, I usually just start in with leftovers after that for mini meals when I get hungry.
Sometimes I make up a big batch of banana chocolate chip pancakes on the weekend and eat them all week (with milk). (These are homemade with whole wheat pastry flour that I do not grind up myself, eggs, various dairy products, leaveners, and of course bananas and chocolate chips. The bananas can be left out or something else squishy like sweet potatoes can be subbed. The dairy products can be mixed-and-matched: milk, yogurt, sour cream.) I also sometimes make French toast on the weekend. Omelets I'm more likely to have for dinner. Normally I make just cheese omlets, but I like my mom's chili omelets with queso on top and her cheese omelets with chili on top. I also like just mixing a couple of (microwaved) frozen veggie sausages with scrambled eggs and cheese.
I do like oatmeal and finally figured out how to recreate my favorite flavor (cinnamon and spice), but haven't had it in a while for some reason.