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I think the fridge. Sour cream doesn't freeze too well, I don't think.
Fridge will be fine. I would think freezing could compromise the texture (i.e. make it grainy) and it could cause the filling to contract and expand, leading to aesthetic issues. I'm sure the pie will be fine for 3 days in the fridge. Sounds delicious!
A love-hate relationship between two slices of bread.
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