Preheat the oven to 375 degrees F. First, prepare the streusel by mixing bowl all purpose flour, brown sugar, cinnamon, and a pinch of salt. Then pour in melted butter and mix until crumbles form. Place the bowl in the refrigerator.
Then, begin preparing the biscuit topping in a separate bowl. Combine all purpose flour, sugar, baking powder, cinnamon, kosher salt, and cubed cold butter. Toss to coat the butter in the flour and begin pinching the flour into the flour mixture (you can use a pastry cutter if you have one). This should take about about 3-5 minutes.
Once the butter is incorporated, add in buttermilk and vanilla extract. Gently knead until the dough comes together, about 2-3 minutes (it may look a little shaggy at first but keep going). Place in the refrigerator.
Place sliced peaches into a large bowl and add all of the filling ingredients together - brown sugar, sugar, cinnamon, nutmeg, lemon juice, vanilla extract, almond extract, kosher salt, kosher salt, melted butter, and cornstarch. Toss everything together until well combined.
Add the peaches into a 12-inch cast iron skillet. Remove the biscuit dough and streusel from the refrigerator. Break pieces of the biscuit dough off and add on top of the peaches in clumps. Then sprinkle the streusel on top of the batter.
Bake for 45-50 minutes on the center rack, until the peaches are bubbling and the top is golden brown.
Notes
Choose the Right Peaches: Use ripe, but not overly soft, ripe peaches for the best flavor and texture. If using canned peaches, drain them well and opt for those packed in juice rather than syrup.
Don't slice the peaches too thinly or else they'll become too soft and mushy in the oven. You want them to be about a 1/2 inch to 3/4 inch in thickness.
If the topping is browning too quickly, cover it loosely with aluminum foil.
Variations
Use canned peaches: you'll need 2 15oz jars of canned peaches. Drain one can and keep the juice from the other. Add the peaches to the cast iron pan and add only the spices and the extracts. Omit the sugar, butter, and cornstarch. Prepare the cobbler topping and streusel as instructed.
Peach Cobbler with Cake Mix: try my cake mix peach cobbler recipe! It's a quicker and super easy way to make peach cobbler that's just as delicious!
Add Almonds on Top: add sliced almond on top of the cobbler for added crunch!
Peach Bourbon Cobbler: Add a splash of bourbon to the peach filling for a hint of richness and complexity.