Preheat oven to 350°F.
Whisk flour, baking powder, salt, and cinnamon in a bowl.
Beat butter with an electric mixer for 2 minutes, then add sugar and beat for 2 more minutes.
Add eggs one at a time, mixing well after each.
Mix in vanilla extract.
Gradually add half of the dry ingredients, then buttermilk, then the rest of the dry ingredients, mixing until just combined.
Pour ⅔ of the batter into the pan over the caramel and peaches.
Spread the chopped peaches and 1 cup of crumble on top.
Add the remaining batter and smooth it out, then sprinkle another cup of crumble on top.
Tap the pan to release air bubbles.
Bake for about 1 hour, checking with a toothpick for doneness.