Preheat oven 350 degrees. Spray 9x13 glass pan with non stick cooking spray and set aside.
In a large bowl, stir flour, soda, salt, powder, spices and sugar until combined. Create a well in the dry ingredients and measure the remaining wet into the well. Stir together until just incorporated and pour into prepared pan. Bake 30-35 minutes or until toothpick comes out clean after inserted. Cool 10 minutes.
Microwave nutella 20-30 seconds until runny. Pour over warm cake and spread. Serve warm.