First, place the chicken tenders in a bowl and sprinkle them with the smoked paprika and cayenne powder. Use your hands or a pair of tongs to toss the chicken until each tender is evenly coated with the spices. Set the seasoned chicken aside while you prepare the skillet.
Heat a cast-iron skillet over high heat and add 3 tablespoons of the butter. Once the butter has completely melted and starts to sizzle, carefully place the seasoned chicken tenders in the skillet in a single layer. Cook them for 1-2 minutes without moving them to get a nice brown sear, then flip and cook the other side for another minute.
Push the chicken tenders to one side of the skillet to make space. Add the remaining tablespoon of butter to the empty area. Once it melts, add the minced garlic and cook for about 30 seconds until it becomes fragrant, then sprinkle the Italian seasoning over the chicken.
Stir everything together, combining the garlic and seasonings with the chicken. Add the salt and lemon juice, and continue to cook, stirring frequently, until the chicken is cooked through and lightly charred. Finally, turn off the heat, add the chopped parsley, and stir one last time to combine.