Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking dish with cooking spray.

Whisk egg substitute, milk, salt, and mustard together in a bowl.

Layer hash brown patties over the bottom of the prepared baking dish, then cover with Canadian bacon and Cheddar-Jack cheese. Pour egg mixture over top. Cover the dish with aluminum foil.

Bake in the preheated oven for 1 hour. Remove the foil and continue to bake until a knife inserted in the center comes out clean and the edges are golden brown, about 15 more minutes.