In a large mixing bowl, whisk together melted butter, Dijon mustard, minced garlic, lemon juice, smoked paprika, salt, black pepper, and red pepper flakes until smooth.
Add chicken chunks to the bowl and coat evenly with the marinade. Let marinate for at least 30 minutes.
Preheat oven to 400°F (200°C) and line a baking sheet with parchment paper.
Arrange marinated chicken on the baking sheet and bake for 15-20 minutes until cooked through and crispy on the outside.
Garnish with chopped parsley and serve warm.
Notes
Store leftovers in the fridge for up to 3 days. Reheat in the oven for best results.