In a bowl combine streusel ingredients (rolled oats, oat flour, maple syrup, cinnamon). Mix it with hands until its sticky and keep it aside.
Preheat oven at 350-degree Fahrenheit and prepare a muffin tray with muffin liners.
In a large bowl, combine oat flour, baking powder, salt and pumpkin pie spice. Mix it well.
Now, pour in soaked flaxmeal, pumpkin puree, maple syrup, vanilla extract and oat milk into the flour mixture. Whip it into a thick batter.
Scoop the batter, with an ice cream scoop, into the 12 cups of the muffin tray (the cups would be ¾ filled evenly). Now, with the help of your hands, sprinkle the streusel generously on each muffins in the tray.
Place the muffin tray in the middle rack of the oven and bake it for 25 minutes or until the tester comes out clean. Once done, turn it off and take it out of the oven and place it on a counter to cool down.
In the meantime, combine glaze ingredients (cashew nuts, oat milk, maple syrup) in a blender and blend it smooth. Keep it aside.
Once the muffins cool down, drizzle the glaze generously and enjoy!