In a small bowl, combine panko breadcrumbs and milk to create a panade; let sit for 5 minutes until a paste forms.
In a large mixing bowl, combine the ground chicken, panade, minced garlic, grated onion, salt, pepper, and paprika.
Gently incorporate the ingredients by hand until just combined, ensuring the chicken is not over-compressed.
Divide the mixture into 4 equal portions (approximately 125g each) and form into patties 3/4-inch thick.
Heat olive oil in a heavy-bottomed skillet or cast iron pan over medium heat.
Place patties in the pan and sear for 5 to 6 minutes per side.
Use a meat thermometer to verify an internal temperature of 165°F (74°C).
Remove from the pan and let the patties rest for 3 minutes before assembling on buns.