Peel and slice apples. Toss with sugars, cinnamon and flour. Set aside.
Roll crust to make slightly larger to fit 10-inch glass pie pan. Fit bottom crust in pie pan. Turn in apple mixture and dot with butter. Put crust on top and crimp edges of crust together.
Preheat oven to 450 degrees F (230 degrees C).
Wet hands with water and dampen top of pie. Sprinkle with additional sugar. Puncture top of pie with fork so the steam can escape.
Bake for 15 minutes in preheated oven. Reduce heat to 350 degrees F (175 degrees C) and continue baking for about 45 minutes more, until crust is golden brown. It's a good practice to place a piece of aluminum foil slightly larger than the pie under the pie plate to catch overflows. Serve warm.