Melt butter in a pan. Add flour and cook for 1 minute (this is your roux).
Slowly whisk in milk until smooth and thickened.
Stir in chicken, vegetables, garlic powder, onion powder, salt, pepper, and herbs.
Cook for 2–3 minutes until everything is coated in creamy sauce. Remove from heat.
Grease a muffin tray. Line each cup with pastry or biscuit dough, pressing gently into shape.
Spoon chicken mixture into each cup.
Cover with another small piece of pastry or leave open-top (your choice).
Brush tops with egg wash (optional for golden color).
Bake at 180°C (350°F) for 20–25 minutes, or until golden and crispy.
Let them cool for 5–10 minutes before removing from tray.