Using the food processor, pulse oats until resembles a coarse flour. Pour into a medium bowl and combine with pastry flour, baking powder, and salt.
In a separate bowl whisk together coconut oil, eggs, maple syrup, and 3/4 cup coconut milk. Add more coconut milk if consistency is too dry and resembles more of a dough than batter.
Gently fold in blackberries.
Evenly scoop in to muffin tin and sprinkle with coconut flakes. Bake until muffin springs back and is starting to golden, 18-20 minutes.