Boil Pasta: Bring a large pot of water to a rolling boil and stir in the salt. Add the elbow macaroni and cook for about 7 to 8 minutes, until tender but not mushy.
1 tablespoon salt, 8 ounces elbow macaroni
Mix Cheese: Drain the macaroni in a colander, then immediately transfer the hot pasta to a large bowl. Add the shredded mozzarella and stir well until the cheese melts and the pasta becomes sticky and evenly coated.
1 ½ cups shredded low-moisture mozzarella cheese
Mold Brain: Line a medium round bowl with plastic wrap, leaving enough hanging over the edges to fold over the top later. Pack the cheesy macaroni tightly into the lined bowl, pressing it down firmly with a spatula so it holds together.
Let It Set: Fold the extra plastic wrap over the top of the pasta and let it sit for 10 minutes. This helps the pasta firm up just enough to flip without collapsing into a cheesy crime scene.
Heat Sauce: While the pasta brain sets, pour the marinara sauce into a small saucepan. Warm it over medium-low heat for about 5 minutes, stirring occasionally, until heated through.
2 cups marinara sauce
Shape Brain: Unfold the plastic wrap from the top of the bowl. Place a large flat serving plate upside down over the bowl, then carefully flip them together. Lift off the bowl and peel away the plastic wrap. Use the back of a chef knife or a spoon to press a deep line down the center of the pasta, creating two brain hemispheres.
Add Sauce: Use a silicone pastry brush to paint the warm marinara sauce over the pasta brain, letting it settle into the center line and all the little pasta ridges for that wonderfully gross Halloween look. Serve immediately.