Preheat the oven to 375 degrees Fahrenheit.
Line a muffin tin with 12 liners and set aside.
Whisk together all wet ingredients in a large mixing bowl.
Whisk in the all purpose flour, oat flour, baking powder and salt. Be sure to spoon and level the flours.
Fold in the poppy seeds and blueberries.
Scoop into the prepared muffin tray, filling each all the way to the top.
Top with a few extra blueberries if desired.
Bake for 25-30 minutes or until a toothpick comes out clean.
Let cool in the tray for about 15 minutes, then carefully remove onto a wire rack to finish cooling.
Whisk together the sugar and lemon juice for the glaze until a smooth consistency is formed.
Drizzle on top of the muffins once cooled and enjoy!