Preheat oven to 350 degrees, and spray an 8x8 casserole dish with non-stick cooking spray, set aside.
Fill a large pot with water and bring to a boil on the stove top over high heat.
Once water is boiling, add pasta shells from the two boxes, and boil 10-12 minutes, set cheese packets aside
Meanwhile, chop broccoli florets into small, bite sized, pieces, and place in a colander, in your sink,
Melt 2 Tbs of butter, and stir the melted butter, stuffing mix, and parmesan cheese together. Set aside.
When pasta shells are done cooking, pour the pasta shells and water over the broccoli in the colander. The hot water will par-cook the broccoli so it cooks faster in the casserole.
In the same pot you cooked the noodles in, add the remaining 2 Tbs butter, and the 3/4 cup of milk, as well as the two cheese packets, and stir well. The pot should be hot enough to melt the butter, but if it is not, put over medium heat and stir until butter is melted, and everything is well mixed.
Dump shells and broccoli into the pot, and stir, coating everything well. Add in the mozzarella cheese, and stir.
Dump into prepared casserole dish.
Top with stuffing mixture, and spread evenly across the top of the casserole.
Bake for 10-15 minutes until top is crunchy and golden brown.