Preheat the oven at 350F or 180C.
Add all the wet ingredients into a bowl and whisk until well combined. Set aside.
Add all the dry ingredients into a bowl and mix until well combined.
Add the wet to the dry ingredients and mix until well combined. The batter is smooth and thick.
Add the chocolate chips and chopped roasted nuts, if using. Mix until combined.
Pour batter into an 8x8 inch pan lined with parchment paper. Spread evenly.
Bake at the middle rack for 15 to 20 minutes. I prefer to bake for only 15 minutes as the texture will be fudgier. It is done when the surface feels soft and spongy. Do not overbake as the texture will become dry and cakey.
Cool completely.
You can slice into 9 or 16 servings. In the video, I sliced into 16 servings.
These fudgy brownies can be kept at room temperature for a few days provided you have a cool and dry climate. Otherwise, it's best to refrigerate earlier for up to 1 week or frozen for months.
To reheat the brownies, just warm up in the microwave for a few seconds before serving.