After trying many cobbler recipes, I have declared this one the winner! I was always a bit puritanical about using a biscuit topping but in the end this cakelike one is so much better at soaking up the fruit! It's really like an upside down cake. Use as much fruit as you possibly can fit in your baking dish!

Will any fruit do or is this recipe particular to blueberries?

Any fruit within reason... I cannot vouch for tropical fruits like bananas or papayas. But I have now made it with several berries and with peaches!

Oh also, I never like to buy buttermilk so I often just use yogurt!

Any particular kind of yogurt?

I personally only buy the Greek yogurt. The reason you need it is that the acidity activates the baking soda in this recipe.