Step 1: Preheat your oven to 350°F (175°C) for even baking.
Step 2: Grease a 9-inch round cake pan and line the bottom with parchment paper.
Step 3: In a double boiler or microwave-safe bowl, melt the chopped baking chocolate and coconut oil.
Step 4: Whisk together cocoa powder, ground cinnamon, and sea salt in a separate bowl.
Step 5: Combine melted chocolate and coconut oil with pure maple syrup and vanilla extract.
Step 6: Add eggs one at a time, whisking well after each addition.
Step 7: Gradually fold the dry ingredients into the wet mixture using a spatula.
Step 8: Pour the batter into the prepared cake pan and smooth the top.
Step 9: Bake for 25-30 minutes until the edges are set and the center is slightly soft.
Step 10: Cool in the pan for 10 minutes, then invert onto a wire rack to cool completely.