Preheat oven to 375°F; grease a 9x13-inch dish.

Cook shells according to package until slightly underdone; drain and set aside to cool.

Mix chili, 1 cup cheddar, sour cream, and chili powder in a medium bowl until combined.

Carefully fill shells with chili mixture; arrange in dish.

Top with remaining 1/2 cup cheese and salsa.

Bake 20-25 minutes until cheese melts and bubbles.

Garnish with green onions; serve.