Position the oven rack to the middle of the oven and preheat to 350ºF.
In a small bowl, mix the flaxseed with water and set aside for 5 minutes to thicken.
In a large bowl mix together the oat flour, rolled oats, baking powder, coconut sugar, cinnamon, and salt.
Next, add the zest, lemon juice, vanilla, milk, and the thickened flax mixture and mix together until combined and no dry spots remain. Fold in the raspberries.
Distribute the batter into the muffin pan (scoop a heaping 1/3 cup of batter for each muffin – you should get 9 muffins) and bake for 22 to 25 minutes until the muffins are browned and slightly firm to touch.
Let the muffins cool for 10 minutes in the muffin pan and then transfer to a cooling rack to cool completely. If not enjoyed within a day or two of baking, freeze the muffins to maintain freshness.