Well, good try! Just use this experience to better prepare yourself for next time. Cooking a nice meal isn't any different than building a nice motor. Don't be afraid of cooking from one bad experience dude! Some suggestions from this experience:
For the chicken, poach (poke) it and set it in the marinade, cover tightly, and put in the fridge the morning of the day your going to grill.
For the mac and cheese, don't add quite so much water/milk as this time (regardless of what the package says, just remember how much you used this time,) and towards the end of the cooking down, cook it down/reduce the liquid with the lid off. Milk will make it creamier/richer than water.
For some great baked potatoes, poach the potatoes, roll them in EVOO (extra virgin olive oil), you can put some herbs on them if you want, then wrap them in foil, and either bake on the grill or pop in the over for about 400* for 40mins-hour depending on how hot your oven is since they vary. When they're done, let them cool for about 20 mins inside the foil, slice down the middle and add some fresh chives/bacon/sour cream/butter/lightly salt or whatever to taste.
You can make that an awesome meal dude, just try again!
My Dinner build thread (first time BBQing)
Keep us posted!
