Combine all the ingredients except the apples in a small bowl. Mix together until crumbly.
Use a knife or apple corer, and take the core out of each apple being careful not to cut through the bottom. Make the hole a little bigger by scooping out a little extra apple after you take the core out.
In a crockpot, pour ½ cup water, set the apples down inside, and fill each one with the oat mixture.
Reserve the extra oat mixture to add some to each apple in the last few minutes of cooking to fill back up to the top.
Cook the apples on high for 1 ½ to 2 hours.
Optional: Top with Ice-cream and or Caramel Sauce.