Apple Pie

My mum has been bringing home lots of apples from the grocery store lately and they don't always get eaten before they go bad, so this week I decided to make a pie with them before they were unusable.

7 cups apples, peeled and sliced (I used gala apples and I cut up about 7, I didn't actually measure)
2 tbsp lemon juice (I think I ended up using more than this)
1 cup sugar
1/4 cup flour
1 tsp cinnamon
1/4 tsp nutmeg
2 tbsp butter or margarine, cut into squares (I didn't measure this part either)
1 egg yolk
1 tbsp water
1 double pie crust (I used this pastry recipe)

Preheat oven to 425. Prepare pie shell in a 9 inch(ish) plate. Toss apples with lemon juice in a large bowl. In a separate bowl combine sugar, flour, cinnamon and nutmeg. Toss this mixture in with the apples. Pour into pie shell. Top with the butter pieces. Cover with pastry top, seal the edges then stab holes in the top for the air to escape. Combine egg yolk and water, brush over top of pie. Place pie on a tinfoil covered cookie sheet (to catch the drippings). Bake at 425 for 15 minutes. Reduce heat to 350 and cook for another 40-45 minutes.