Preheat the oven to 400ºF.
Cook chopped bacon slices in a large skillet, stirring occasionally, until crisp and fully cooked. Turn off the heat and transfer the bacon to a small bowl using a slotted spoon.
Combine peeled and diced Yukon gold potatoes, mayonnaise, shredded mild cheddar cheese, minced garlic cloves, Dijon mustard, kosher salt, and black pepper together in a large bowl. Stir in the bacon.
Transfer the potato mixture to a cast-iron or broiler-safe high-sided skillet and spread into an even layer. Bake until the potatoes are tender.
Remove the skillet from the oven, turn the oven on to broil, and sprinkle more shredded cheddar cheese evenly over the top. Return the skillet to the oven and broil until the cheese on top is melted and browned in spots.
Let the potatoes cool for 10 minutes. Garnish with the remaining bacon and finely chopped fresh chives.
