Preheat the oven to 400ºF. In a bowl, stir together the room-temperature butter, olive oil, minced garlic, garlic powder, chopped parsley, and salt until relatively smooth (a few small lumps of butter are okay).
Cut the loaf in half, into two 12" long pieces, then cut each piece open lengthwise. Lay the bread on a baking sheet cut sides facing up. Spread the garlic butter mixture evenly over the open surfaces of the bread.*
Bake the bread for 10-15 minutes, or until the edges are golden brown and crispy. Bake for less time if you prefer a softer garlic bread, and more time if you prefer a crispier garlic bread. Cut the bread into 2-inch sections and serve hot.
*Once the garlic butter is spread over the surface of the bread it can be frozen in gallon-sized freezer bags and baked at a later date. The bread can be baked straight from the freezer, although it may take a minute or two longer to brown.