Preheat the oven to 180C/350F. Line an 8 x 8-inch pan with parchment paper and set aside.
In a small bowl, whisk together your dry ingredients. In a separate larger bowl, whisk together your softened butter, sweetener, eggs, cocoa powder, and vanilla extract, until combined.
Gently add in your dry ingredients and mix until fully incorporated. If using chocolate chips, fold them through at the end.
Transfer your brownie batter into the lined pan. Bake for 35 minutes, or until a skewer comes out just clean. Remove from the oven and allow to cool completely, before slicing.
* See post for eggless/vegan option.TO STORE: Leftover brownies should be stored in the refrigerator in a sealed container. Brownies will keep well for at least 7 days.TO FREEZE: Place brownies in a ziplock bag and store in the freezer for up to 6 months.