Preheat your oven to 375°F. Meanwhile, bring a large pot of salted water to a boil and cook the ziti according to package directions, but drain it 1-2 minutes early—the pasta will continue cooking in the oven, so you want it slightly al dente. This prevents the final dish from becoming mushy. Set the drained pasta aside in a large bowl.

In a large skillet over medium-high heat, cook the ground beef, breaking it apart as it cooks, until browned (about 5-7 minutes). Drain off excess fat and set the beef aside. In the same skillet, melt the butter over medium heat, then add the diced onion and cook for 2-3 minutes until softened. Add the minced garlic and cook for 1 minute until fragrant. Pour in the spaghetti sauce and stir in the onion powder, Italian seasoning, salt, and red pepper flakes. Return the cooked beef to the pan and simmer the sauce for 5 minutes to let flavors blend together.

In a medium bowl, combine the ricotta, egg, sugar, 1/3 cup Parmesan, and 1/4 tsp salt. Mix until smooth and well combined. This creamy mixture will add richness between the layers of pasta and sauce.

Pour the beef and sauce mixture from Step 2 into the bowl with the cooked pasta from Step 1. Mix everything together thoroughly, making sure the sauce coats all the pasta evenly.

Spread half of the pasta mixture into a 9x13 inch baking dish. Spoon the ricotta mixture from Step 3 over the top and spread it into an even layer. I like to use an offset spatula or the back of a spoon to distribute it evenly so every bite has that creamy richness. Sprinkle 1.25 cups of mozzarella over the ricotta layer. Then add the remaining pasta mixture and top with the remaining 1.25 cups mozzarella and 1/2 cup Parmesan.

Bake the assembled ziti in the preheated 375°F oven for 25-30 minutes, until the top is golden brown and the cheese is melted and bubbly. Remove from the oven and let it rest for 5 minutes before serving—this allows the layers to set slightly and makes serving much cleaner. I find that skipping this rest time results in a sloppy first scoop, so it's worth the wait!