Step 1: Preheat your oven to 400°F (200°C). Wash and scrub the Russet potatoes thoroughly under cold running water. Pat them completely dry.
Step 2: Pierce each potato several times with a fork. Rub each potato lightly with olive oil and sprinkle generously with coarse salt. Place directly on the oven rack.
Step 3: Bake for 50-70 minutes, or until the potatoes are tender when squeezed and easily pierced with a fork. Remove from the oven and let cool enough to handle, about 10-15 minutes.
Step 4: Carefully slice each potato in half lengthwise. Using a spoon, scoop out the soft potato flesh into a large mixing bowl, leaving about a 1/4-inch border of potato attached to the skin to create a sturdy shell.
Step 5: Add the softened butter, softened cream cheese, and sour cream to the scooped potato flesh. Mash with a potato masher or an electric mixer on low speed until mostly smooth. (A few small lumps are fine for texture!)
Step 6: Stir in half (1/2 cup) of the grated cheddar cheese, chopped chives, garlic powder, onion powder, salt, and black pepper. Mix until just combined. Taste and adjust seasonings as needed.
Step 7: Spoon the potato mixture back into the reserved potato skins, mounding it slightly. Place the filled potato halves back on a baking sheet.
Step 8: Sprinkle the remaining 1/2 cup of cheddar cheese evenly over the tops of the potatoes.
Step 9: Bake for another 15-20 minutes, or until the cheese is melted and bubbly and the tops are lightly golden brown.
Step 10: Garnish with extra fresh chives, bacon bits, or a dollop of sour cream, if desired, and serve immediately.