Preheat the oven to 425°F/220°C. Line a standard 12-cup muffin tin with liners. I recommend lightly oiling the muffin liners, as there’s very little oil in this recipe.
Zest the lemon(s) to get 1 tablespoon of zest, and then juice to get ¼ cup juice. Mix the lemon juice with the almond milk and set aside - it will quickly curdle, like buttermilk.
In a large bowl, combine the 1 ½ cups flour, almond flour, baking powder, and salt. Make a well in the center and then add in the lemon zest, almond milk-lemon juice mixture, yogurt, maple syrup, mashed banana, oil, and vanilla.
Stir the wet ingredients into the dry with a wooden spoon, stirring until they're just mixed - about 12 strokes. The batter should be lumpy and not smooth. Overmixing will cause the muffins to become dense.
Toss together the blueberries with the extra 3 tablespoons of flour.
Using a silicone spatula, fold the poppy seeds and blueberries into the muffin batter.
Using a cookie dough or mini ice cream scoop, dollop the muffin batter evenly into the prepared muffin cups.
Reduce the temperature to 350°F/175°C and bake the muffins for 23-25 minutes, or until a toothpick inserted in the center comes out with just a few crumbs.
If desired, make the Lemon Icing. Whisk together all of the ingredients in a bowl until you achieve your desired consistency. Add more liquid for a thinner glaze. Drizzle a little icing onto each muffin and top with a zest of lemon.