Preheat oven to 350 degrees. Prepare a 5 x 9 loaf pan by greasing with coconut oil.
In a medium bowl, whisk together oat flour, coconut flour, and baking soda. Set aside.
In a separate bowl, whisk eggs.
Add maple syrup, lemon juice, vanilla extract, and lemon zest to beaten eggs.
Add coconut sugar into wet mixture and stir until smooth.
Now, pour in melted and cooled coconut oil to wet mixture. Stir to combine.
Combine wet and dry ingredients. Fold together until completely incorporated.
Batter should be thick and a little sticky! Transfer to prepared loaf tin. Use a utensil to smooth the batter out.
Finally, top with 1 tbsp of coconut sugar.
Bake in the oven at 350 degrees for 20-25 minutes, until edges are golden brown.
Let cool for 10 minutes before slicing and serving. Store covered on the counter!