Preheat your oven to 375°F and cook the pasta according to package directions, draining it 1-2 minutes before it reaches full tenderness. This prevents mushiness once the bake finishes cooking in the oven.

In a large skillet, melt butter over medium-high heat and sauté the diced onion until softened, about 3 minutes. Add minced garlic and cook for another minute until fragrant, then add the chicken pieces and cook until golden on all sides—approximately 8-10 minutes.

Pour the chicken broth into the skillet and scrape any browned bits from the bottom using a wooden spoon. This cheesy chicken pasta bake crowd recipe gets its depth from those flavorful bits, so don't skip this step.

Reduce heat to medium and stir in the heavy cream, cheddar cheese, mozzarella cheese, Italian seasoning, salt, and black pepper. Simmer for 3-4 minutes until the cheese melts completely and the sauce becomes silky smooth.

Combine the cooked pasta with the chicken sauce in a 9x13 baking dish, stirring gently until every piece of pasta is coated. Mix the breadcrumbs, parmesan cheese, and olive oil in a small bowl, then sprinkle this mixture evenly across the top of the pasta.

Transfer to the oven and bake for 15-18 minutes until the breadcrumb topping turns golden brown and the edges bubble gently. Remove from heat and let it rest for 5 minutes before serving.