Peel and slice the peaches over a wide bowl to catch the juices.
Add to the bowl the vanilla, sugar, lemon juice, and salt. Set aside.
Cut the cold butter into small cubes (about 1/4 cubic inch), and place in a small bowl.
Add the flour and sugar. Use a pastry blender or fork to cut the dry ingredients into the butter, so that the butter is coated with the flour and sugar.
Pour the cold water over the mixture and combine until the dough can be shaped into a ball. It won't be smooth and perfect; that's okay.
Wrap the dough in plastic and chill for an hour or more.
Cover your working surface with a dusting of flour. Roll out the dough into a large circle, about 2-3 inches larger than your pie plate.
Position the rolled out dough over the pie plate so that the dough hangs evenly over the rim.
Sprinkle 1 tbsp. flour over the dough in the pan. Arrange peach slices in a circular pattern atop the dough, then pour in the juice.
Fold the edges of the crust up over the filling to form a shell, leaving the center of the pie open.
Bake for 45-50 minutes, until the crust is golden brown and the filling is bubbly.
Remove and cool a bit. Add raspberries to the top of the filling. Sprinkle the galette with powdered sugar, if desired.
Serve warm with vanilla ice cream and additional raspberries.