Preheat oven to 350° F.
Add ½ cup marinara sauce to the empty 9x9 (or similar in size) baking dish. Spread it out evenly so the entire base is covered.
Next, evenly distribute half of the ravioli on top of the sauce base. Then add another layer of ½ cup sauce and spread over the ravioli.
Top the sauced ravioli with the entire package of chicken nuggets and repeat with another ½ cup marinara sauce and spread it evenly over the chicken nuggets.
Add remaining ravioli into an even layer, spread the remaining 1 cup of marinara sauce over the ravioli, and top with mozzarella slices.
Place in oven for 25 minutes, until heated through. For a bubbling cheesy top, broil for an additional 5 minutes. Let cool 5 minutes before serving.
