Here's a couple of fast and pretty easy ideas (bet you could handle more complicated one, but not sure exactly what else you have in the house to work with).
For the chicken, assuming it's cut up in pieces. First take a zip lock bag and add a cup or so of rice krispies, about a tsp of salt and same amount of paprika. Crush either by pounding or with your hands. Just don't do it hard enough to rip the bag. Then coat the chicken with a thin layer of mayonnaise. Drop the chicken in the bag, one piece at a time and shake to coat. Bake in an oven you preheated to 350 for about half an hour or a little bit longer if the chicken is on the bone. I was kinda scared to try this the first time with the mayo, but a friend insisted it was awesome. Trust me, she was right! It adds a great flavor and keeps the chicken super moist.
For the Beef: How about a meatloaf? Mix together the chopped meat, one egg, some ketchup, breadcrumbs, a couple dashes of wostershire sauce if you have it, garlic and onion powders, and some salt. Shape into a loaf and bake it about 40 minutes.
If you want to list more ingredients you have in the house, or what kind of food you and your brother like, I'd be glad to come up with more ideas. But wanted to stick with what you were likely to have on hand for sure.
As for the brownies, do you have any cream cheese in the house? If you do you can mix together a package of cream cheese, an egg, some vanilla drop it by spoonfuls across the top of the made brownie mix in the pan before baking, run a knife through in both directions (up the pan then across) to swirl it in. Or if you have 2 kinds of puddings you could make a chocolate one and a vanilla one, bake the brownies up when backed then layer in a dish with brownies and alternating puddings. If you did this with cake it would be called a Trifle. Not sure what it would be called with brownies...maybe just yummy LOL.
Hope this helped!