Preheat oven to 375°F (190°C) and line muffin cups with muffin papers.
In a large mixing bowl, mix the oats, all-purpose and whole wheat flours, cornmeal, flax flour, baking powder, and salt.
In a separate bowl, beat the eggs. Mix in the lemon zest, oil, brown sugar, and milk.
Add the liquid ingredients to the dry ingredients. Mix until the dry ingredients have been moistened.
Gently fold the raspberries into the batter. Fill the lined muffin cups 2/3 full.
Bake for 20–30 minutes, until the muffins are lightly browned and a toothpick inserted in the centre comes out clean.
