Place cubed potatoes in a large bowl, cover with cold water, and soak for 10 minutes to remove excess starch. Drain well and pat completely dry with paper towels.

In a large cast-iron or heavy-bottomed skillet over medium heat, cook chopped bacon until crispy, about 6-8 minutes. Remove bacon with a slotted spoon, leaving fat in the skillet. Reserve 3 tablespoons of bacon fat.

Heat reserved bacon fat in the same skillet over medium-high heat. Add potatoes in a single layer (cook in batches if needed). Cook undisturbed for 5-7 minutes until golden brown on one side, then flip and cook another 5-7 minutes.

Reduce heat to medium. Add diced onion and cook for 3-4 minutes until softened. Add minced garlic and cook 1 minute until fragrant. Sprinkle seasoning blend evenly over potatoes and toss to coat.

Continue cooking for 5-7 more minutes, stirring occasionally, until potatoes are deeply golden and crispy. Add cooked bacon back to the skillet and toss. Stir in butter if using for extra richness.

Remove from heat, sprinkle with fresh parsley, and serve immediately in the skillet while hot and crispy.