Preheat your grill to 350° F, prepare for indirect grilling. Bring a small pot of water to a boil and hard boil two eggs. Cook the rice until al dente – it will finish cooking in the casserole.
Grease your favorite casserole dish (approx. 1½ qt.). Use a fork to flake the salmon, chop the eggs into tiny chunks, and mix them all together with the rice and shredded mozzarella. Season to taste with a little pepper.
In a medium saucepan, melt ¼ cup of butter, sprinkle with mustard powder. Add the milk, stirring constantly. Slowly bring the mixture to a simmer. Milk scorches easily, so keep the heat low and keep stirring. Add the cream cheese and continue stirring while the cream cheese melts. Pour the sauce over the salmon mixture and stir it through.
Crush the Cheese Nips into small pieces. Melt the 2 tbsp. of butter and add it to the crushed crackers. Stir to coat the crackers. Sprinkle the cracker crumbs over the top of the casserole.
Bake the whole thing on your grill over indirect heat, uncovered for 30 minutes.
Serve the Salmon Casserole family style, hot off the grill in all of its bubbling glory, along with seasonal vegetables or your favorite salad and some fresh bread.