Preheat the oven to 350ºF (175ºC).
In a large bowl, whisk together the cake flour, baking powder, salt, and cinnamon.
In a separate bowl, beat the butter with an electric mixer for about 2 minutes. Add the sugar and beat for an additional 2 minutes.
Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract.
Add half of the dry ingredients to the butter mixture, mixing on low speed until just combined. Add the buttermilk, mixing again until incorporated.
Add the remaining dry ingredients and fold until smooth, being careful not to overmix.
Pour 2/3 of the batter into the bundt pan over the caramel and peaches. Smooth the batter with a spatula.
Sprinkle the diced peaches on top of the batter, followed by 1 cup of the biscuit crumble.
Gently press down the peaches and crumble, then pour the remaining batter on top, smoothing with a spatula. Top with the remaining 1 cup of biscuit crumble.
Tap the pan a few times to release air bubbles, then bake for 1 hour, or until a toothpick inserted into the center comes out clean.
If the cake is browning too quickly, cover with foil.