Preheat your oven to 350°F. While it heats, finely dice the onion into 1/4-inch pieces and measure out all dry seasonings (brown sugar, Italian seasoning, garlic powder, black pepper, and red pepper flakes) into a small bowl. This prep work ensures everything is ready when you need it and prevents scrambling mid-recipe.

Bring a large pot of salted water to a boil and cook the mostaccioli until just firm (al dente), about 1-2 minutes under the package time—it will finish cooking in the oven. While the pasta cooks, combine the room-temperature ricotta, eggs, and romano cheese in a bowl and whisk until smooth and evenly blended. This prevents lumps in your final dish and ensures even distribution throughout the layers.

In a large skillet over medium-high heat, cook the diced onion in the browned beef for 3-4 minutes until the onion softens and becomes translucent. Add the seasoning mixture from Step 1 and stir for 1 minute to bloom the spices and release their flavors. Pour in both jars of pasta sauce, then drain the cooked mostaccioli from Step 2 and fold it into the sauce, tossing gently to coat everything evenly. I like to taste this sauce and adjust the seasoning if needed—sometimes I add a pinch more salt depending on the sauce brand you choose.

Spread half of the pasta-meat mixture from Step 3 into a 9x13-inch baking dish. Spoon the ricotta mixture from Step 2 evenly over the pasta layer, then top with the remaining pasta-meat mixture. Scatter the halved meatballs over the surface, distributing them evenly for better coverage in each serving. Finish by sprinkling the freshly grated parmesan over the top—fresh parmesan melts and browns more beautifully than pre-grated varieties.

Bake uncovered for 35-40 minutes until the top is golden brown and the sauce bubbles around the edges. The internal temperature should reach 165°F for food safety. Let the casserole rest for 5 minutes before serving—this allows the layers to set slightly and makes portioning cleaner. Garnish with fresh basil or oregano if desired for a fresh herb brightness that cuts through the richness.