Preheat oven to 350℉.
Butter an 8x8 baking dish. Set asise.
Add the sugar, flour, and a pinch of Kosher salt to a bowl. Add in the cubed butter, and mix it into the dry ingredients using the back of a fork. Set side.
Layer the sliced apples in the baking dish. Mix the water and vanilla and pour over the apples. Sprinkle the cinnamon and nutmeg over the apples.
Using a large soon or your hands, sprinkle the butter-flour topping evenly over the apples.
Place in the oven and bake for approximately 50 minutes, until golden brown and bubbly.
Remove from the oven and allow to rest for 5 minutes.