Line a large rimmed baking sheet with paper towels. Place wire racks on top of paper towels and set aside.
Wash and peel potatoes, then grate them using the large holes of a box grater. Combine grated potatoes and onion in a clean, thin kitchen towel. Squeeze out as much liquid as possible, then transfer them to a large mixing bowl.
Add Colby Jack cheese, whisked egg, flour, salt, garlic powder, and black pepper to bowl. Stir until evenly combined.
Add about a quarter inch of oil to a large skillet and heat over medium heat.
Once oil is hot, drop large spoonfuls of potato mixture (about 3-4 tbsp. each) into pan, cooking 3-4 latkes at a time, leaving space between them. Gently flatten each portion into a disc.
Cook for about 2-3 minutes per side, flipping once, until golden brown and crispy.
Transfer cooked latkes to wire racks on prepared baking sheet and immediately sprinkle each with a pinch of salt.