This is an easy recipe, almost a not-recipe. But it's so satisfyingly weird looking and comfort-foody (and not in the least bit good for you).
Cook a lot of celentani (the corkscrewy macaroni things) and elbow macaroni (not too small, the elbows). Stir in as much ricotta as you wish... I tend to use half of the smallish tub (a pint?) for a half box of celentani plus a half bag of elbows... sorry I'm not more precise. Resist the temptation to add anything that adds color. It won't help the look. You may add a little garlic if you like, provided that it's minced fine; OR a very little nutmeg does fine. Not both. You can add a little plain yogurt to add "slip" to the texture if you like, but NOT too much if you want it to set up and look all brainy.
Put this mixture into a cellophane-or-foil-lined bowl about the size of a cranium. Let it rest a moment in the bowl to firm while you heat some marinara sauce.
Take a bigger, flatter serving bowl, nest it over the full cranium bowl so that they are concave-to-concave, and turn out the pasta carefully into the bowl, hoping it retains its shape. Indent down the middle to make "hemispheres" with a suitably long skinny object. THEN remove the foil or plastic.
Spoon the marinara into the bowl so it surrounds the "brains"... but don't go crazy with it. It can spoil the wonderful illusion.
I want to hear your variations on this theme... mine's easy and yummy (believe it or not, it is tasty when very simple).