01 -
Set oven to 175°C and allow to preheat fully.
02 -
In a large mixing bowl, blend together the shredded potatoes, chopped onion, cream of mushroom soup, cream of celery soup, and half of the grated Colby cheese until evenly mixed.
03 -
Grease a 23 x 33 cm baking dish with spray oil to prevent sticking.
04 -
Evenly spread the potato mixture into the prepared baking dish, smoothing the top.
05 -
Scatter the remaining Colby cheese over the surface, then distribute small dollops of margarine evenly on top.
06 -
Bake in the preheated oven for 45 to 60 minutes, or until the cheese is bubbling and begins to brown at the peaks.