Prep work- Start by pre heating your oven to 350 degrees and bringing a large pot of water to boil. Cook the lasagna sheets per the package instructions, make sure to add a splash of olive oil so the pasta doesn't stick together. Dice the chicken breast into small bite size pieces and season with Italian seasoning, garlic powder, onion powder, salt & pepper. Shred the cheese if you are not using pre shredded.
In a skillet over medium-high heat add olive oil and chicken pieces. Pan sear until they are cooked thoroughly, and the internal temp reaches 165 degrees. (should take around 7-8 minutes) Remove chicken from skillet and set aside.
For the sauce, in a skillet over medium-high heat, melt the butter and add chopped onions. Sauté the onions until they start to soften (3-5 minutes), add the minced garlic and cook for an additional 1-2 minutes. Turn heat to lowest setting and add heavy whipping cream, stir to combine and then add the parmesan cheese. Make sure to constantly stir until it thickens up and develops a smooth creamy consistency. Turn off the heat and give it a taste it. If it needs salt & pepper, season to your preference.
Spread a thin layer of sauce to the bottom of your 7x11 casserole dish, then add a single layer of lasagna sheets and then evenly spread half the amount of chicken on top. Sprinkle a layer of mozzarella cheese and top with some of the alfredo sauce. Repeat this step for the additional layer. For the final layer, cover with a single layer of lasagna sheets and top with alittle more alfredo sauce and mozzarella cheese, sprinkle some parsley flakes on top if desired. Cover with foil and bake for 45 minutes. Remove cover and broil for 2-3 minutes or until the lasagna forms a nice golden-brown crust.
Remove from oven and let rest for 15 minutes and enjoy!