Place a wooden spoon on each side of the potato so that they are parallel to each other. Cut vertical slits about 3-5mm apart. The wooden spoons prevent you from cutting all the way through. If you choose to use baby potatoes, you can place chopsticks on either side of the potato instead.
Arrange the potatoes on a baking sheet.
Combine the melted butter, oil, garlic and salt. Brush each potato with this mixture and bake initially for 30 minutes.
Take the potatoes out of the oven, brush them again with the mixture. Try and get some between the slices to put the flavour through the potato. Return to the oven for about another 25-30 minutes or until the potatoes are golden and the flesh is soft.