In a medium slow cooker, add butter, both sugars, cinnamon, water and flour and stir to combine.

Peel and core apples and working quickly cut them in half and slice into quarter inch slices.

Add apples to butter mixture, stir, cover and cook on high for four hours.

While apples are cooking, make topping.

Preheat oven to 375 degrees F.

Line a sheet tray with parchment paper.

In a food processor, mix flour, both sugars, baking soda, cinnamon and salt until combined.

Add cold butter pats and pulse a few times until they are pea sized.

Add oats and pulse a few times just to incorporate, or add in by hand.

Pour onto prepared sheet tray and bake five minutes. Remove, toss with a spatula and bake 10 minutes. Remove toss and bake just to crisp, another 2-3 minutes.

Remove and cool and store in an air tight container until service.

After four hours, portion hot apple mixture into bowls, sprinkle on topping and serve with vanilla ice cream.