4 cups chopped Vidalia onions
Melt butter in a large nonstick skillet over medium heat; add onions and cook, stirring often, until golden and very tender, 20-30 minutes. Gradually add spinach, stirring just until wilted, about 1 minute. Sprinkle with 1/2 teaspoon salt and 1/4 teaspoon pepper. Remove from heat and let stand 30 minutes.
Stir together onion and spinach mixture, sour cream, and chives in a medium bowl. Stir in the remaining 1/2 teaspoon salt and 1/4 teaspoon pepper. Cover and chill 30 minutes or up to 2 days.
Serve with chips and veggies