Heat oven to 200C/180C fan/gas 6 and grease a 12-hole muffin tin. In a frying pan over a medium heat, fry the bacon for 5 mins until golden. Let it cool, then chop into chunks and set aside
In a bowl, combine the flour, baking powder and 1 tsp sea salt. Using your fingers, mix the butter into the flour mixture until it resembles breadcrumbs
In a small bowl, whisk together the milk, oil and egg. Tip into the dry mixture, and gently mix until the flour mixture is mostly moistened (lumps will remain). Stir in the bacon, chives and cheese, then spoon the batter into the muffin tin.
Put the muffin tin in the oven and bake for 20 mins or until the tops are golden brown. Serve warm.