No power - hot breakfast Christmas Day?
I've never been but how about Markham Station. It's 24 hours so I assume might have a shot at being open today?
I love United Bakers. at Bathurst/Lawrence plaza. Not a greasy spoon but 5 mins from 401, kid friendly, delicious food. Not in your area but it's something....
More southerly would be the Thompson Diner, which gets largely favourable reviews on Chowhound.