Dice mozzarella cheese into 1 cm cubes.

Dice bacon into 1 cm squares.

Fry bacon in a frying pan until crispy (without oil).

Wash potatoes.

Wrap potatoes individually in plastic wrap.

Microwave potatoes until soft (about 5 minutes, depending on size).

Peel potatoes while hot.

Remove any bigger eyes from potatoes.

Place potatoes in a bowl.

Mash potatoes with a masher or fork.

Combine mashed potatoes with bacon, milk, salt, and pepper.

Mix thoroughly and set aside to cool.

Scoop about 1 1/2 to 2 tablespoons of cooled potato mixture in your hands.

Bury about 2 cubes of cheese in the potato mixture.

Form into round balls.

Repeat until you have 12 balls.

Make sure to fold in the cheese well so it won't stick out.

Coat each ball with flour, then beaten egg, and then panko in that order.

Deep-fry the croquettes until golden brown.

Arrange on a plate and serve with ketchup if desired.