Line 2 12-cup standard muffin pans with muffin liners or grease with unsalted butter
Roast the raw walnuts on low-medium heat until they are a little darker and crispy
Step 1: Streusel Topping
In a small to medium-sized bowl, whisk together flour, tapioca starch, oats, sugars, cinnamon, and salt.
Add walnut oil and butter, then mash the mixture together with a fork until the butter is evenly incorporated and looks clumpy, like smashed peas.
Set aside in the refrigerator until you need to use it.
Step 2: Dry Mix
In a medium sized mixing bowl, whisk together flour, tapioca starch, oats, sugars, salt, baking soda, and baking powder until well combined.
Toss in the chopped walnuts and mix until evenly incorporated.
Step 3: Wet Mix
In a separate, larger bowl (or KitchenAid bowl), beat (or whisk) the eggs and granulated sugar on high for about 5-7 minutes. The mixture will be fluffier and pale. When the whisk is lifted out of the bowl, the mixture makes lovely "ribbons" or trails.
Add the walnut oil and buttermilk and gradually increase to high so as not to splatter everywhere. Mix on high for 1-2 minutes.
Now peel, measure and mash the bananas, in a separate bowl. You can use a fork or fingers, just don't mash it up too much. Add to the wet mix, and mix briefly on high until it is well incorporated.
Step 4: Combine Mixes
Tip! Be careful not to over mix the dry ingredients into the wet mix. (You don't want to lose all the air you got from whisking those eggs!)
Gradually (I like to add the dry mix in 3 rounds) and gently add the dry mixture to the wet mixture. Ideally, it should be more like a folding motion rather than a mixing or stirring one.
It's better to have a little dry mix still lumpy than to over mix.
Step 5: Scoop & Streusel It
I like to use a medium-sized ice cream scooper to scoop the batter into the muffin liners. I'll add a scoop to all the cups, and then add then try to add evenly across all of them with the remaining batter.
Get the streusel out of the refrigerator and break it up with a fork, back into those pea-sized lumps.
Spread a little of the topping all over all of the cups, then I go back over to make sure to get it up to the edges. Every loose crumb is worth scooching into a cup!
Step 6: Bake
Make sure the oven has been at desired temperature for at least a half-hour before baking.
Place both of the pans in the middle of the oven.
Bake for approximately 27 minutes (25-28). It's easy to over bake these. Don't forget, they'll keep baking in the pans a little when they come out of the oven. I know they're ready by the look of the edges of the muffins, they'll turn a yummy reddish-golden brown.
You'll definitely know they're ready when you poke a toothpick or cake tester into the middle of the middle muffin and it comes out clean.
Cool for 10 minutes before glazing or serving.
Optional: Glazing
Add the cocount milk and coconut oil to a small bowl or pan.
Heat it up just enough to melt the oil, but not too hot. I use a microwave to heat up for 30 seconds.
Crumble in some toasted coconut if you have some, it adds a lovely and surprising extra crunch!
Add the light brown sugar and whisk together until it turns a nice golden color.
Add the wet mixture to the powdered sugar and mix until it gets to a nice consistency. I like it on the thicker side as I find it is still quite runny when warm.