Line 18 holes of 2 x 12-hole nonstick mini muffin tins with paper mini muffin cases or lightly grease. Sift the flour, baking powder and salt into a large bowl, then stir in the spring onion and pepper.
Whisk together the egg, milk, oil and pesto in a jug. Pour into the dry ingredients and stir until just combined.
Spoon the mixture into the prepared mini muffin tins, then push a piece of cheese into the centre of each one and scatter over the pine nuts.
Bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 12–15 minutes until risen and golden. Serve warm.