Preheat oven to 350F/180C. Line a muffin pan with paper liners or grease well.
In a large bowl, whisk together the oat flour, coconut flour, brown rice flour, coconut sugar, and baking powder. Set aside.
In another bowl, add the applesauce, coconut milk, coconut oil, and flaxseeds. Whisk until uniform.
Add the wet ingredients to the dry and stir until you get a uniform, very thick but pourable batter. Spoon batter into prepared muffin pan, filling each liner to about 3/4 of the way full.
Bake for 25-30 minutes, until lightly browned on top and a toothpick comes out clean when inserted.
Cool for 5 minutes in the pan, then remove and cool completely on a wire rack.
To make the frosting, add the cashews, coconut cream, coconut oil, maple syrup, lemon juice, and vanilla to a blender. Blend until very smooth, scraping down the sides as needed. Add a bit more coconut cream if needed to blend.
Leave it as is or add the pitaya powder or turmeric and blend again. Alternatively, if you want all three colors, divide the mixture into three, leave 1/3 plain and add turmeric powder and pitaya powder to the other thirds. Refrigerate frosting for at least 4 hours, or ideally overnight.
Transfer into a piping bag and frost muffins.
Garnish with fresh berries or fruit and serve immediately. Store leftovers in the refrigerator.