Pre-heat oven to 180°C or 350°F. Line a muffin tin with parchment paper liners.
Combine the almond flour, oat flour, cacao powder, baking powder, baking soda, and sea salt in a medium bowl.
Whisk together the eggs, coconut sugar, almond milk, coconut oil, and vanilla extract in a large bowl.
Add the dry ingredients into the wet ingredients and whisk to combine completely.
Stir in the dark chocolate chips.
Divide batter evenly between 12 cupcake liners.
Bake for 18-20 minutes. To test if they're ready, insert a toothpick. If there are tiny pieces of cake or chocolate attached to the toothpick, the cupcakes are ready! Don't wait until the toothpick comes out completely clean.
Let cupcakes cool for 10 minutes before removing and cooling completely on a wire rack.
To make the frosting, place the melted chocolate in a small bowl and whisk in the cold almond milk and maple syrup until smooth. Stir in an additional 1/2-1 tbsp cold almond milk if needed.
Spread the chocolate frosting over the cupcakes (once they've cooled down).