Put your peeled, halved potatoes into a large stock pot with water, and bring to a boil. Once the water boils, you'll want to cook the potatoes for about 10 minutes or so. You'll know they're ready when a sharp knife easily goes into them.
When the 10 minutes or so are up, drain the potatoes, and put them into a small Pyrex pan or a pie tin and let them cool a bit.
Now for the "twice" part. Drizzle your olive oil over the potatoes, and cut pats of butter and place those over the potatoes. Toss the potatoes to insure that they're all covered with some of the oil.
Put your pan into the oven and cook for around 30 to 45 minutes, until they're nice and golden brown. You'll want to turn the potatoes about half-way through them cooking to make sure that they brown consistently in the oven.
And that's it.