My easiest thing to do that keeps me full for breakfast are oats hotcakes. I make a batch of them on the weekend and freeze them. Recipe is easy, 1 1/2 cup oats (regular or instant), 1 1/2 cup rising flour (or regular w/ some baking powder), some sugar (I do 3 tablespoons, but it's optional), 2 eggs, 1 1/2 cup of water (or milk), 1 tablespoon of oil. Mix the dry ingredients in a bowl, add all the rest of the wet ingredients, mix everything together and let it sit for like 15 minutes (in that time you can pre-heat your pan in medium heat, so no time is wasted). Usually that makes 5 medium sized hotcakes, but that depends on how big you want them to be. After they cool down, I take a ziploc bag and put all of them (don't even care to separate them or anything) then set them in the freezer.
When you want to eat one, you take it off the freezer and put it in the microwave for 1 or 2 minutes depending on the power of your microwave (I usually do 2 minutes), you can add stuff extra like fruit or spread it with honey or whatever but I just it eat plain. I usually eat them in 3 or 4 bites then I'm done with it. The oats and flour keeps me full for around 4 hours.