Fry the bacon lardons until cooked to your liking. (Are you a soft, melt-in-your-mouth bacon person, or a crispy bacon cruncher person?) Remove with a slotted spoon and place on some kitchen paper. Do not throw the bacon fat away!
Whisk the flour, sugar, baking powder and baking soda together in a bowl.
In another bowl, mix together the buttermilk, yogurt/sour cream, egg, melted butter and bacon fat from the bacon you just fried.
Make a well in the centre of the dry ingredients and pour the wet ingredients and the bacon lardons in (you can keep a few to one side to top the pancakes with, if you want). Carefully stir with a spoon until just incorporated - a few lumps here and there is a good sign. Leave to sit at room temperature for at least 10 minutes and up to 30.
When you're ready to make the pancakes, heat a frying pan over a medium heat and melt one teaspoon of butter in it. Pour around ⅓ cup of the pancake mixture into the pan and leave to cook for around 2-3 minutes, or until the top of the pancake is full of popping air bubbles. Flip the pancake over and cook for around 30-60 seconds or until brown. Place in a warm oven whilst cooking the others. Repeat the same steps with the remainder of the batter, remembering to grease the pan with 1 teaspoon of butter every time.