Place flour in a food processor with salt, sugar, and rosemary. Cut in butter a few pulses at a time until the butter is bean shaped. Add in the buttermilk and continue to pulse until the butter is pea-sized. Dump out onto a clean surface and work together and knead until it forms a ball. Cut in two parts making one part slightly larger than the other. Form each into a flattened ball and place each portion into a large zip-lock bag. 

Chill the dough in the fridge for 30 minutes.

Peel and thinly slice the apples. Place in a medium sized bowl. Add the remaining ingredients to the apples, and mix until uniform.

On a well-floured surface, roll out the larger disk of pie dough, and place in a 9-inch glass pie pan. Dump the apples into the pie crust, and evenly distribute.  On a well-floured surface, roll out the remaining smaller disk of dough, and cut into one-inch thick strips, and place on the pie in a diagonal lattice. Crimp edges. Cut excess dough hanging off the pie pan, and fold inward.

Bake at 425 degrees for 30 minutes. Turn oven temperature down to 350 degrees, and bake for another 10-15 minutes.

Cool pie to room temperature before cutting.