Combine the mashed potatoes, egg, seasoned salt, ground black pepper, flour, and green onion in a large bowl and mix well.
Shape the potato mixture into 3-inch patties.
Heat a medium-sized skillet over medium heat. Add the butter.
When the butter is melted, cook the potato pancakes on both sides until they’re heated through and browned. This should take 4 to 5 minutes on the first side, and 3 to 4 minutes on the other side.
You may need to cook the potato pancakes in small batches. You may also need to add addtional butter to the bottom of the pan in the additional batches.
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Recipe Tips
If you want to keep these warm just until serving, place the potato pancakes in an oven-proof dish and place into an oven heated to 200 degrees.