To make topping: Combine flour, sugar and nutmeg in a mixing bowl; stir well to mix and stir in sliced almonds. Stir in butter evenly. Set aside for 5 minutes, then, using your fingertips, break the mixture into 1/4 to 1/2-inch crumbs. Set aside again while you prepare the filling.
Preheat oven to 400 degrees and set racks at middle level. Roll out bottom crust and arrange in 9-inch Pyrex plate.
To make filling: Peel the peaches by cutting a cross in the blossom end of each and dropping them three at a time into a pan of boiling water. Remove after 20 or 30 seconds with a slotted spoon or skimmer and drop them into a bowl of ice water. If the peaches are ripe, the skin will slip off easily. If it does not, remove the skin with a sharp stainless steel paring knife. (If you peel it with a knife, include an extra peach for what you have peeled away.) Hold each peeled peach gently in your left hand over a mixing bowl (if you are left handed reverse.) With a stainless steel paring knife make a cut through to the pit, from stem to blossom end. Make another cut about 3/4-inch to the right of the first one along the outside of the peach. Angle the knife blade back so the cuts meet at the pit. Twist the knife blade upward slightly as a wedge of peach will fall into the bowl. Continue in the same manner around the peach, cutting it into 8 to 10 wedges. Discard the pit and repeat with remaining peaches. Add remaining ingredients, except the butter, to the peaches and stir gently with a rubber spatula to combine. Pour filling into the prepared pastry shell and smooth. Dot with the butter.
Scatter the crumb topping evenly over the filling. Place pie on the bottom rack of the oven and bake for 15 minutes. Lower the temperature to 350 degrees and move pie to the middle rack. Bake another 30 minutes, or until the crust and crumble are a deep golden and the juices are just beginning to bubble up. Cool the pie on a rack and serve warm or room temperature.