Peel and dice the potatoes and place them in a large pot filled with cold water. Bring to a boil and cook until fork tender, about 15 to 20 minutes. Drain and return to the pot. Mash with the butter, milk, salt, pepper and granulated garlic until the mixture comes together and is smooth. Allow to cool to room temperature. Stir in the bacon, scallions or chives, cheese, and ¼ cup flour until combined.
Shape the mixture into balls about the size of large golf balls and place on a baking sheet. Place the remaining flour in a shallow dish. Whisk the eggs in a separate shallow dish. And combine the plain and panko bread crumbs in a third shallow dish. To coat the croquettes, toss the potato balls, in flour, then dip in eggs, and then roll around in bread crumbs. Return the croquettes to the baking sheet and then freeze for about 30 minutes before frying.
Fill a medium sauce pot about halfway with vegetable or canola oil and bring up to 360°F, with a deep-fry or candy thermometer. Once hot, fry the croquettes in batches until golden crispy all around, about 4 to 5 minutes. Drain well and transfer to a plate lined with paper towels to soak up any excess oil. Then transfer to a wire rack, set over a baking sheet to prevent from getting soggy. Continue frying until all the croquettes are fried.
To make the sauce, combine the sour cream, garlic, scallions or chives, salt and pepper until smooth. Serve the croquettes with the sauce on the side for dipping. Enjoy!