Sugar Free Berries Cobbler

Our Family has gone sugar-free since mid October.  At first it wasn't easy, but as we learned how sugar is toxic to our bodies it has become easier.  Yah gave me an idea on how to deal with temptation at the beginning of our life change, when the sweet called out to me I just reminded myself it was poison, no matter how it looked smell or how I remembered how it tasted, poison was poison... this helped not only me but my girls as well.  We have tried several sugar-free desserts some good others will never be tried again.  One we found that that has turned into a favorite because it's sweet and EASY. 

Sugar-Free Berries Cobbler

1 cup of self-rise flour
1 cup of butter (we use 1/2 cup butter and 1/2 cup of coconut oil)
1 cup of milk
1 cup of Splenda
bag of frozen mixed berries

Mix the first four ingredients together, dump into a casserole dish.  Sprinkle the berries with some stevia or splenda, mix and dump on top of the batter mix.  Bake at 375 degrees for 1 hour.  Serve warm or cold.

I'm not thrilled about using splenda but until I can figure out how to subsitute a cup of splenda with stevia we'll be using splenda (for this dessert only) with that said does any one have an idea how to do this?  Stevia would only have to take maybe 1-2 tsp (if that much) to sweeten this dish.  I'm concerned about the volume lost about a whole cup of volume lost. It would be a great help if anyone has idea's on this and would be willing to share them with me ;-) 

Shabbat Shalom