Combine about 1 cup sugar, 2-4 tablespoons flour, 1/2-1 teaspoon cinnamon and a dash of nutmeg, and toss with the apples.
Pile into a pastry-lined pie plate (here's one possible recipe) and dot with a bit of butter.
Top with some more rolled-out pastry, flute the edges, and cut a couple of slits. (You could also do a lattice top - Michelle's vote - or a crumble top - my vote. What's your favorite way to finish an apple pie?)