Preheat oven to 350 degrees F. Grease a 9-inch round cake pan with oil.
In a medium-sized mixing bowl, whisk together the dry ingredients and set aside.
Place the ground chia seeds into a blender. Add the hot water and blend for a few seconds to combine. Let rest for about 2 minutes to form a gel. Then add the remaining wet ingredients and blend again to combine. Alternatively, you can add the ground chia seeds and hot water to a medium-sized mixing bowl and quickly whisk together (they will clump up if not whisked immediately). Let rest for a minute or two, then add the remaining wet ingredients and whisk together well.
Pour the wet ingredients into dry, scraping everything out using a silicone spatula, and whisk together.
Pour batter into the cake pan and bake for about 30 to 35 minutes.
Cool completely before adding any glaze or frosting.