Place bacon into a non-stick frying pan over medium-high heat. Cook, stirring often, for 4 minutes until light golden. Remove to a plate.
Increase heat to high. Add oil and mushrooms to frying pan. Cook for 5 minutes until tender. Set aside to cool.
Preheat oven to 200ºC. Grease 6 x 3/4-cup capacity Texas muffin pans*.
Sift flour, baking powder and salt and pepper into a bowl. Add cheese and chives. Whisk butter, eggs and milk in a jug. Pour into dry ingredients. Stir gently until almost combined.
Fold through the bacon and mushrooms. Spoon the mixture into prepared pan. Bake for 20–22 minutes or until cooked, when tested with a skewer. Stand 5 minutes in pan before turning out. Serve warm.