Line 20 sections of 2 x 12-section mini muffin trays with mini paper cake cases. Put the flour, baking powder and salt in a bowl. Stir in the cheese and chives until evenly mixed.
Whisk together the melted butter, milk and egg with a fork in a jug and add to the bowl. Stir well to form a thick paste. Divide the mixture between the paper cases.
Bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 10–12 minutes or until risen and pale golden. Transfer to a wire rack. Serve warm or cold.