Add apples and the lemon juice to a large bowl and toss.
Add in the 1/3 cup brown sugar, 2 teaspoons ground cinnamon, and a pinch of salt. Combine well.
Pour the mixture into the bottom of a slow cooker that has been sprayed with non stick cooking spray.
In the same bowl, combine oats, pecans, flour, 1/3 cup brown sugar, 1 teaspoon ground cinnamon, a pinch of salt, and butter.
Spread this mixture on top of the apples already in the slow cooker.
Place a folded dish towel over the top of the slow cooker before adding the lid.
Cook on high for 3-4 hours or low for 6-8 hours.
Serve this up warm right from the slow cooker and top with a serving of ice cream.
Please note that I have used this towel method several times without issue but it is not recommended by all manufacturers. Be sure to read your manual and check your slow cooker often to make sure the towel is not too hot.