Dough: Using a cheese grater, shred the butter as you would a block of cheese. The butter needs to be very cold. Keep it in the fridge until ready to use. In a stand mixer with paddle attachment, mix all dry ingredients. Toss the butter in and allow to mix slowly until it resembles wet sand/pea size pieces of butter. Stream in cold water as needed until dough comes together. Place in fridge (covered) for 15-30 minutes.
Macerated peaches: Mix all ingredients together, set aside.
Roll out dough into family style, using all dough, or 6" individual disks.
To assemble: Have a sheet pan covered with a silat. Place prepared dough on top of silat. Spread the almond paste in the center of the galette dough ring. Top with macerated peaches. Fold the dough ends over top of the peaches, leaving the top open.
Brush with egg wash and sprinkle with almonds and raw sugar. Bake at 350 degrees for 40 minutes. Turn every 15-20 minutes to evenly brown (unless using convection).