Step 1: Preheat your oven to 200°C (400°F). Make sure your oven rack is in the middle position for even baking.
Step 2: Thoroughly scrub your potatoes under cold running water to remove any dirt. Dry them completely with a kitchen towel. This is crucial for crispy skin!
Step 3: Pierce each potato several times all over with a fork or the tip of a sharp knife. This allows steam to escape during baking, preventing the potatoes from bursting and ensuring a fluffy interior.
Step 4: Drizzle the dried, pierced potatoes generously with olive oil and rub it all over, ensuring the entire surface is coated. Sprinkle liberally with sea salt, gently rubbing it into the skin.
Step 5: Place the prepared potatoes directly on the middle oven rack. Baking them directly on the rack (rather than a baking tray) allows for better air circulation around the entire potato, promoting an all-over crispy skin. Place a baking sheet on the rack below to catch any drips.
Step 6: Bake for 1 hour to 1 hour 15 minutes, or until the skin is deeply golden, incredibly crispy, and the potato yields easily when squeezed. The cooking time will vary depending on the size of your potatoes. A good test is to insert a skewer or fork; it should slide in with very little resistance.
Step 7: Once baked, carefully remove the potatoes from the oven. Using oven mitts, immediately slice each potato lengthwise down the middle, being careful not to cut all the way through the bottom. Pinch the ends of the potato gently to push the fluffy interior upwards, creating a cavity for your toppings.
Step 8: Generously butter the inside of each potato, allowing it to melt into the hot, fluffy flesh. Add a hefty sprinkle of shredded cheddar cheese and return to the warm oven for a minute or two if you want extra melty cheese. Finally, garnish with fresh chopped chives and your favorite extra toppings. Serve immediately and enjoy the perfect jacket potato!