Preheat oven to 375 degrees F, position the rack on the middle of the oven.
In a large bowl or stand mixer, cream the butter and sugar until light. About 3-5 minutes.
In a separate, smaller bowl, sift together the flour, baking powder, cinnamon and salt.
Alternate adding the flour mixture and the milk to the creamed mixture.* if your peaches are particularly juicy, add in less milk. The batter should be thick and loosely hold it’s shape. Think of it like very pliable cookie dough.
Fold in the peaches, being careful to not overwork the batter.
Line the 9 inch bread pan with parchment paper and then spoon the mixture into the loaf pan. Sprinkle with a dusting of Demerara sugar (optional but encouraged).
Bake in the oven for 60 minutes, checking to see if a toothpick comes out clean.
At 45 minutes cover the top of the bread with a tinfoil tent to prevent from over browning.
If your peaches are particularly juicy, reduce milk to 1/4 cup. This way you prevent the batter from getting too wet.
If you want to make these into muffins, raise your oven temperature to 375°F and bake for 30-35 minutes.