Place chicken strips in a bowl of milk and let soak for 20–30 minutes.
Preheat oven to 400°F (200°C).
Cut butter into pieces and place in a 9×13 baking dish. Melt butter in the preheated oven.
Remove pan and spread melted butter evenly across the bottom.
In a large zip-top bag, combine flour, panko breadcrumbs, garlic powder, salt, pepper, and paprika.
Shake excess milk off chicken strips. Add half of the chicken at a time into the bag and shake to coat evenly.
Arrange coated chicken strips in the buttered pan, leaving space between each piece.
Bake for 10–12 minutes. Flip using tongs and bake another 10–12 minutes, until golden and cooked through.
If needed, bake an additional 5–10 minutes, being careful not to overcook.
Remove from oven and place on paper towels to drain excess butter.
Garnish with chopped parsley and serve immediately with marinara sauce.