Place the oven rack in the venter position and pre-heat the oven to 400° F and grease an 8x8 pan.
Add chopped peaches, sugar, fresh lemon juice, flour, salt, nutmeg, cinnamon and vanilla extract to a large mixing bowl and toss to combine.
Transfer the peaches mixture to the greased 8x8 baking pan and spread into an even layer.
Sprinkle the brown sugar over the peach mixture.
Bake the peach mixture for 10 minutes.
Meanwhile, add the flour 1/2 cup of the sugar, salt, and the baking powder to a separate mixing bowl and stir to combine.
Chop the chilled butter into very small pieces with a sharp knife.
Add to the bowl and combine with the dry ingredients with your fingers until small pebble-sized pieces form.
Add the heavy cream and the water to the flour mixture and stir with a fork until all the dry ingredients are moist and somewhat sticky. Be careful not to overwork your dough.
Remove the baking pan with the peach mixture from the oven and carefully spoon the dough over the top making sure the dough is the same thickness throughout. For a more rustic look, leave spaces between your spoonfuls of dough as pictured.
Return the pan to the oven and bake for another 10-15 minutes, or until the top begins to brown.
Meanwhile, add your egg white to a small bowl with a teaspoon of water and mix well to create an egg white wash.
Remove from the oven and brush the top with the egg white wash and sprinkle the remaining sugar on top.
Return to the oven to finish baking, approximately 10-15 minutes. Remove from the oven when the tops are golden brown.
Allow the pan to cool slightly before serving with ice cream or whipped cream!