Preheat your oven to 350°F (175°C). This ensures that your cake bakes evenly and achieves the perfect texture.
Grease your 9x13 inch baking pan with a little avocado oil or line it with parchment paper for easy removal later.
In a large mixing bowl, whisk together the gluten-free all-purpose flour, coconut sugar, raw cacao powder (if using), baking powder, and sea salt until well combined.
In another bowl, mix together the water, avocado oil, and vanilla extract. Stir until the mixture is well-blended.
Pour the wet mixture into the bowl with the dry ingredients. Using a whisk, mix until just combined. Be careful not to overmix; a few lumps are okay!
Transfer the batter into the prepared baking pan, spreading it evenly with a spatula.
Place the pan in the preheated oven and bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, remove the cake from the oven and let it cool in the pan for about 10 minutes. Then, transfer it to a cooling rack to cool completely before slicing and serving.
