Cook bacon in an 8-in. cast iron skillet over medium heat for 5 to 6 minutes or until crispy. Remove from skillet; reserve 1 Tbsp. drippings in the skillet. Drain bacon on paper towels.

Add butter to bacon drippings in skillet; cook over medium heat until melted. Add half of the onions to the skillet. Cook for 3 to 5 minutes or until onions begin to soften, stirring frequently. Add remaining onions to the skillet; cook for 3 minutes. Stir in garlic salt and baking soda. Reduce heat to medium-low; cook for 45 to 55 minutes more or until onions have a jam-like consistency and are golden brown, stirring frequently.

Preheat oven to 425°. Stir together cream cheese blend, mayonnaise and Worcestershire sauce in a medium bowl until smooth. Set aside 2 Tbsp. bacon for garnish. Stir remaining bacon and 2 Tbsp. chives into mayonnaise mixture.

Stir ¼ cup cooked onion mixture into the mayonnaise mixture. Then add mayonnaise mixture to remaining onion mixture in the skillet; stir until combined.

Bake for 8 to 10 minutes or until heated through. Top with reserved 2 Tbsp. bacon and remaining 1 Tbsp. chives. Serve with pretzel crisps and assorted vegetables for dippers.