In a large skillet over medium-high heat, cook the bacon until crispy, 4-6 minutes. Remove the bacon from the pan and drain on a paper towel-lined plate.
In the same pan, add the garlic. Cook over low heat for about 30 seconds, or until it starts to brown. In a medium bowl, beat 8 eggs and add to the pan, along with the scallions, salt, and pepper. Scramble the eggs until mostly set but still a little wet, about 3 minutes. Remove the pan from the heat.
Peel the potatoes and grate on the large holes of a box grater onto a clean kitchen towel set over a bowl. Wring out any excess liquid.
Transfer the shredded potatoes to a clean, large bowl and add the remaining egg, the flour, and ½ cup (50 g) cheddar cheese, and season with salt and pepper. Mix to combine.
Line a 4-inch (10 cm) diameter bowl with plastic wrap.
Place ½ cup (75 g) of the grated potato mixture in the bowl. Use the back of a spoon to smooth the potatoes against the sides of the bowl in an even layer, creating a divot in the center.
Fill the well with a bit of cheddar cheese, a spoonful of scrambled eggs, a bit of bacon, and top with another sprinkle of cheese.
Pick up the sides of the plastic wrap, twisting to create a sealed ball. Repeat with the remaining ingredients.
Chill the potato balls for 20 minutes.
Preheat the oven to 375°F (190°C). Line a baking sheet with parchment paper or foil and grease with nonstick cooking spray.
Unwrap the balls, place them on the prepared baking sheet, and brush with egg wash. Bake for 35-45 minutes, or until the potatoes are crispy and brown.
Sprinkle with parsley and serve with ketchup on the side.