Not all apple pies have a double pastry crust. Some have a crumble topping.
Personally, I don’t like a pie topping that is thick and sweet, like a streusel. I want it to complement the apple flavor, not to hide it. I want the apples to fill my fork, and have the topping enhance it. I’m also partial to nuts and ginger.
This is what I do:
Crumble Topping For Apple Pie
1/2 cup all-purpose flour
1/2 stick (4 ounces) chilled butter
1 1/2 cups old fashioned rolled oats
1/2 cup (2 ounces) nuts (I prefer walnuts or pecans)
1 tablespoon crystalized ginger
1 tablespoon maple sugar (optional)
1 teaspoon ground cinnamon
1/4 cup demerara or light brown sugar
pinch of salt
Using a food processor, pulse until the nuts and butter become pea-sized.
This makes enough for two pies. Extra topping freezes well, and does not require thawing before use.