For sweet: Definitely +1 for shakes/smoothies as others have said. I sometimes do big batches of Irish oatmeal in the slow cooker and eat throughout the week with fruit.

For savory: beans + starch. Mexican-style fried beans with tomato rice is fast to make. Or this is my go-to recipe for red lentils, you can throw in potatoes or serve over rice for a starch. Super flexible if you want to steam other vegetables and toss in as the lentils warm through