Mix all dry ingreddients together in a bowl.

Melt butter in a microwave safe bowl and mix the melted butter with the dry ingredients. Set aside.

Core apples and fill (pack mixture in) the center of the apples with the oatmeal and butter mixture.

Stand filled apples in the bottom of the slow cooker and pour 1/2 cup of water in the bottom-around the apples.

Place the lid on the slow cooker and cook on high for 2 1/2 hours.

Check tenderness before removing from the slow cooker. They should be tender.

Remove apples from the slow cooker with a spoon to avoid the filling falling out.

Serve alone or with some vanilla ice cream.