In a bowl, mix together the hash browns, cooked onions ... then place in an 8"x8" oven safe baking dish and sprinkle the remaining 1/2 cup of Cheddar Jack cheese on top. Bake at 425 degrees ...
The cheesy sauce layer makes it special and is a ... it’s just less shiny and stretchy. I use a bake-while-you-build approach making this, adding layers to what’s in the oven while it cooks.
Place 1 piece of Boursin on top. Bake 45 to 55 minutes. Cover with foil if Boursin starts to brown. Remove from oven. Allow squash to cool slightly, then remove the cheese, tomatoes, to a large bowl.