Boil your pasta per package instructions and drain it. Make sure you only cook it until al dente.
In a small bowl, mix the baking soda and lemon juice and set them aside for the chemical reaction to finish.
Mix the milk and half and half in a small pot and warm them up well. Grate all your cheese.
In a large pot, melt the butter, add the flour and spices and make a roux. Mix well with a whisk. Let the roux cook for a while until it gets a nutty colour and flavour.
Add the lemon and baking soda mixture and mix well.
Add the milk and half and half and mix well. Your mixture should be hot at this point. If it isn't, keep it over medium heat, mixing continuously until it gets hot but doesn't boil.
Remove the mixture from the heat and gradually mix in your grated cheeses. Mix with a whisk or silicone spatula until melted.
Preheat your oven to 400 degrees Fahrenheit (200 degrees Celsius).
Add the boiled pasta to the sauce and mix well.
Mix all of the crispy topping ingredients together. Butter the cast iron or baking dish.
Pour the mac and cheese in the cast iron skillet or baking dish and sprinkle with the crispy topping.
Bake for 10 minutes or until the crispy topping is lightly browned.