Even though I titled this special occasion, it's really great to have as a warm the heart and tummy dinner. This is a huge recipe that can be halved and put in a 2 1/2 quart baking dish. You can also top this with crushed Ritz crackers with drizzled butter.
Preheat oven to 375 degrees. Shred the cheddar and jack cheeses, stir together and set aside. Meanwhile, pour 2 cups of milk into a large saucepan and warm over medium low heat. Cut up the Velveeta into chunks, add to the saucepan and cook over medium low heat until all of the cheese has melted. Add the additional milk only if needed to thin. Remove from the heat and set aside. Crack the eggs into a separate bowl and lightly whisk. Scoop out some of the cheese sauce and slowly add that to the eggs to temper them, continuously whisking as you add the liquid to the eggs. Once well tempered, add the eggs to the cheese sauce and whisk together until well mixed.
Spray a large casserole pan with non-stick cooking spray. Add half of the elbow noodles and season with salt, pepper and Cajun seasoning. Slice thin layers of butter and spread them around on top of the noodles. Sprinkle 1/2 of the cheddar/jack cheese combo over the noodles. Ladle 1/2 of the Velveeta cheese sauce over that. Repeat the layers of noodles, seasoning, butter, cheddar/jack cheese, cottage cheese and Velveeta sauce.
Cook at 375 degrees, uncovered for 30 to 35 minutes or until bubbly and browned.