Step 1In the bowl of a food processor, combine the almonds and flour and pulse until the almonds are coarsely chopped and combined with the flour. Add the brown and granulated sugars and cinnamon and pulse again until combined. Add the butter cubes and pulse again until the butter is broken up and the mixture is crumbly.
Step 2The crumble topping can also be made by hand: Chop the almonds finely and stir together with the flour, brown and granulated sugars and cinnamon, then add the butter and rub together with your fingers until the butter is broken up and the mixture is crumbly.
Step 1Heat the oven to 350 degrees.
Step 2In a large bowl, whisk together the sugar and flour. Stir in the nectarine slices, coating completely, then stir in the almond extract until evenly combined.
Step 3Pile the nectarine filling into the prepared pie shell, sprinkling over the slices any additional sugar-flour mixture that did not stick to the fruit.
Step 4In a small bowl, whisk the egg to form a wash.
Step 5Brush the edge of the crust with the egg wash. Drizzle the crumble topping over the fruit slices.
Step 6Place the pie in the oven and bake until the crust is a rich golden color and the filling is bubbly and thick, about 1 hour.
Step 7Cool before serving.