For the macaroni and cheese, start by sweating the onions and garlic in melted butter over low heat. Pour in the milk and season with salt and pepper. Let the mixture come to a rolling boil and add the elbow macaroni noodles, then reduce the heat and bring everything to a gentle simmer. Once the milk has reduced, remove the pan from the heat, stir in the grated cheddar cheese, and set aside for later.
Preheat the oven to 350°F. Season the chicken breasts with salt and pepper and make a large horizontal incision in each, creating 2 large chicken breast pockets.
Crush the crackers and mix them with the paprika, onion powder, pepper, garlic powder, and salt. Whisk 2 eggs in a medium-sized bowl and set them up alongside a separate bowl filled with flour. Roll the chicken breasts in flour, dredge them in whisked egg, and coat them in the crushed cracker breading.
Turn a muffin pan upside down and place 2 pieces of parchment paper between the molds. Put a chicken breast pocket on top of each piece of parchment paper and pull the pocket apart at the incision.
Stuff each chicken breast with macaroni and cheese, transfer the muffin pan to the oven, and bake at 350°F for 35 minutes.
While the stuffed chicken breasts are in the oven, prepare the guacamole. Scoop out the fruit of the avocado and mash it against the side of a bowl using a fork. Mix in the chili pepper, lime juice, red onion, salt, and pepper.
Once the stuffed chicken breasts come out of the oven and are cool enough to serve, put a big scoop of guac on top!
