Preheat oven to 375 degrees F. Lightly oil a 12 cup muffin pan or use liners or a silicone pan to prevent sticking.
Add the oat flour to a large bowl. Sift in any of the remaining dry ingredients if they appear clumpy (this is especially helpful with baking soda and powder). Whisk all the dry ingredients together very well. In a smaller bowl, whisk together the coconut milk, maple syrup, vanilla, and vinegar.
Pour the wet mixture into the dry, and whisk until smooth. Stir in the raisins and chopped walnuts, if using.
Evenly divide the batter among the 12 muffin cups. Sprinkle the tops with additional chopped walnuts, if desired.
Bake for 18-20 minutes, or until the muffins are firm when lightly pressed. Alternatively, insert a tooth pick into the center of a muffin to check for doneness. Allow the muffins to cool in the pan for 5 minutes, then transfer to a cooling rack.
To make the glaze, put the coconut butter in a small bowl or mug and microwave for just 10 to 15 seconds or until melted. Use a fork to whisk in the maple syrup and about 2 teaspoons of milk. Add a small amount of turmeric and whisk again until smooth. If the glaze is too thick, add another teaspoon of milk. Taste and adjust sweetness and turmeric as desired.
Store muffins in an airtight container at room temperature for up to 2 days or in the refrigerator up to 5 days. Muffins can also be frozen for longer storage.