Preheat the oven to 350F/180C and line a 9" square baking pan with parchment paper.
In a large bowl, stir together all the dry ingredients - the flour, cocoa powder, sugar, stevia powder, baking powder, baking soda and salt.
Stir in the wet ingredients - skimmed milk, beaten egg and applesauce - until you've got a thick and even batter.
Pour the batter into the prepared pan and bake in the oven for around 20 minutes, until the tops of the brownies have set, but there is still a little wobble in the middle.
Place the baking tin on a wire rack and leave to cool slightly before slicing into 9 squares and serving.