Wash the rosemary sprigs.
Dry rosemary sprigs in oven, bake at 175 degrees for 1 to 1 ½ hours, until the rosemary leaves are brittle.
Gently press the dry rosemary in a mortar and pestle to expel natural oils from the herbs.
Crush the peppercorns with a mortar and pestle to release the flavors and set a side.
Add the pressed rosemary sprigs, crushed peppercorns and garlic powder to a clean glass jar that has a tight top (like a cork stopper).
Using a funnel, pour the olive oil into the jar over the herbs and spices.
Seal the jar tightly and store for one week in a cool, dark place (like the pantry). During this time, the oil will infuse.