Bake potatoes and refrigerate the night before. There easy to handle when you go to slice them.
Mix ranch dressing, green chilies & sour cream the night before. It gives it time to marry the flavors. But not necessary.
Also go ahead and fry the bacon and crumble it. Stick in the refrigerate over night.
Also slice the green onions and put in refrigerator.
The more you do the night before the easier it is the day of the BBQ or party! It's easy peasy!
Preheat oven to 350 degrees.
Slice potatoes with a mandolin. That way potatoes warm evenly. Use a casserole dish 9X13 or larger if you have one. Spray with PAM or what ever you like or even butter it. You don't want it to stick.
Put a layer of potatoes,butter, sour cream then cheese. Till the last layer that's when you use the bacon. The green onions go on after it comes out of oven. Sometimes I just sit aside the green onions in a bowl and let them help them selves as some don't like onions at all! Enjoy!