Slow Cooker Winter Mixed Berry Cobbler

Oh, what a treat this is!  And the best part is that is made with frozen berries, so you can enjoy all the goodness right in the middle of a cold winter.  Is sweet, creamy and simply delicious! Enjoy!
-16 oz frozen mixed berries (blackberries, strawberries, raspberries)
-1 (21 oz) can blueberry pie filling
-1/4 cup sugar
-1 (7 oz) package blueberry muffin mix
-1/3 cup water
-2 Tbs vegetable oil
-whipped topping or vanilla ice cream, to serve
Lightly coat the bottom of your slow cooker with cooking spray.  Add the frozen berries, pie filling and sugar.  Stir well.  Cover and cook on LOW for 3 hours.
In a bowl, combine the muffin mix with the water and oil.  Mix well and drop by spoonfuls on top of the berry mix.  Cover and cook on HIGH for 1 hour or until the toothpick comes out clean.
Turn off the slow cooker, uncover and let it sit for about 1 hour.  
Serve with some ice cream or whipped topping.  Enjoy!