Do ahead: Place a strainer lined with a coffee filter over a bowl. Put the applesauce in the filter and let it drain for 4 hours; it should shed 1/2 cup of liquid., Preheat the oven to 350°F. Lightly grease an 8" square pan., In a medium mixing bowl, whisk together the eggs, salt, vanilla, sugars, and butter (or oil). Stir in the drained applesauce., In a separate bowl, whisk together the cocoa, baking soda, and flour., Gently add the dry ingredients to the wet, stirring until uniformly mixed. Stir in the chips., Transfer the batter to the prepared pan, and bake the brownies for 28 to 30 minutes, until they appear set and a cake tester inserted into the center comes out clean., Remove them from the oven, and cool in the pan before cutting., Store, well-covered, for 4 days at room temperature, or freeze for up to a month.