• Preheat the oven to 350°F (180°C). Line a 9-inch x 5-inch loaf pan with lightly oiled parchment paper. Set it aside.
• In a large mixing bowl, whisk all the dry ingredients: almond flour, all-purpose gluten-free flour, oat flour, baking powder, baking soda, sugar, and gum (if your gluten-free flour blend doesn't contain gum).
• In another bowl, whisk milk, lemon juice, olive oil, and vanilla extract.
• Pour liquid onto the dry ingredients and stir until just combined, then fold in blueberries and stir again to evenly distribute berries in the batter. Don't over mix batter to avoid dense bread.
• Transfer the batter to the loaf pan and bake in the center rack of the oven for 45-65 minutes or until a toothpick inserted in the center of the bread come out clean. Test the baking process every 10 minutes for 45 minutes. Foil the top of the pan if the bread browns too fast.
• Cool down on a cooling rack immediately and wait 3 hours before slicing or glazing.

Glazing

• To glaze, stir powdered sugar and lemon juice. If too thin, add more powdered sugar 1 tablespoon at a time. If too thick, add a bit of water. Adjust until you love the texture of the glazing.
• Drizzle on top of the cooled bread. Add lemon zest if desired.
• Store in the fridge for up to 4 days or freeze up to 3 months in an airtight box.