Heat the oven to 180C/350F, then line and grease a loaf pan with parchment paper. The paper makes the finished loaf easier to lift out, especially since this bread is quite moist.

Whisk the almond flour, coconut flour, sweetener, salt, and baking powder in a large bowl, then stir the eggs, melted butter, Greek yogurt, vanilla extract, and milk together in a separate bowl until smooth. Keeping dry and wet ingredients separate first helps the batter mix evenly without clumps.

Pour the wet mixture into the dry ingredients and stir just until combined, then gently fold in the blueberries. The batter should look thick and scoopable, and a light hand keeps the berries from bursting and turning everything purple.

Spread the batter into the prepared loaf pan and bake for 45 to 50 minutes. The top should turn golden brown, smell nutty and sweet, and a skewer inserted in the center should come out mostly clean with a few moist crumbs.

Leave the bread in the pan until it cools completely before slicing. This resting time helps the crumb set, so the loaf cuts cleanly instead of crumbling while warm.