This recipe comes the closest to the ones that are sold in the stores. Do not substitute Splenda or other sweetner, the sugar in the recipe carmelizes as the brownies bake, making them more sticky (when I used Splenda, they felt like rubber. On the box vital wheat gluten also appears, I learned that it helps the brownies rise as the batter is rich in sugar. I figure about 1/2-1 teaspoon is enough
* I didn't have yogurt at hand but I had some milk and Jello Sugar Free Fat Free Instant Chocolate Pudding. I made the pudding according to recipe on the box and substituted it cup for cup (I omitted the baking soda because the soda is there to offset the acidity in yogurt, no yogurt= no need for soda). The brownies came out even better!