Preheat the oven to 190°C and lightly grease or spray a 12-hole muffin tray with cooking spray.
Sift the flour, baking powder and celery salt into a large bowl, then stir in the cheese and corn and toss to combine.
Whisk the eggs, milk and oil together, then pour the wet ingredients into the dry and fold together until just mixed.
Half-fill muffin holes with mixture, then place a small teaspoon each of cream cheese and pesto in the middle of each one. Cover with remaining mixture.
Bake in the oven for 15-20 minutes or until puffed, golden and spongy when tapped on the top.
Cool for 5 minutes before removing from the tin. Serve warm with extra pesto.