Heat your oven to 400ºF and grease an eight- or nine-inch round casserole dish or square baking pan with non-stick cooking spray.
Set a pot of water to boil over high heat, season well with salt, and cook the macaroni noodles until al dente, then drain and cool slightly. Meanwhile, whisk the eggs, milk, and dry mustard powder together in a bowl and season with salt and pepper.
When the noodles have cooled slightly, transfer them to the prepared baking pan. Scatter over one and a half cups of the cheddar cheese and gently mix to distribute the cheese. Pour the milk and egg mixture over the noodles and set aside while you prepare the topping.
Place the butter crackers into a bowl or a large zip-top bag for the topping and crush them. Add in the ground Parmesan cheese and butter and mix well to combine. Finally, add the remaining cup of grated cheddar cheese and mix to combine. Scatter the topping over the macaroni and bake for 30 to 35 minutes or until set in the middle and golden brown on top.
Serve as is or, if you’re like Myra and Mary, with lots of ketchup and maybe a bit of hot sauce. Enjoy!