I use extra sharp white cheddar but any kind of cheddar cheese works. For the yogurt, I use sheep yogurt, but any yogurt works. To make this bread a bit denser and richer you can add up to ½ cup of yogurt and a little extra cheddar cheese (about 1 to 2 tablespoons). It depends how dense you like your quick breads and this one specifically. More yogurt and cheese will also make it a bit tangier which I like. I've made it both ways and both are good.I recommend a bread pan around 8 inches by 5 inches.