Preheat the oven to 350°F and line a baking sheet with parchment paper; optionally place a wire rack on the sheet.
In a shallow dish whisk together 1/2 cup milk and 2 large eggs until combined.
Place 4 cups Corn Flakes, 1 tablespoon chopped parsley, 1 teaspoon smoked paprika, 1/2 teaspoon kosher salt, and 1/4 teaspoon black pepper in a food processor and pulse until the cereal is breadcrumb-like; transfer to a second shallow dish.
Working one tender at a time, dip each chicken tender into the milk-and-egg mixture, flipping to coat both sides, then press into the cornflake mixture to fully coat; transfer to the prepared baking sheet in a single layer.
Spray the tops of the coated tenders lightly with cooking spray and bake for 15 minutes, flipping halfway through, until golden and cooked through.
While the chicken bakes, stir together 1/2 cup mayonnaise, 2 tablespoons ketchup, 1 tablespoon minced onion, 1 tablespoon sweet relish, and a pinch of kosher salt to make the special sauce.
Serve the baked cornflake chicken tenders warm with the special sauce and an extra sprinkle of parsley if desired.