Preheat and prep: Heat the oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners or lightly grease with oil spray.

Mix dry ingredients: In a large bowl, whisk 2 cups almond flour, 2 tablespoons coconut flour, 1/2 cup granulated keto sweetener, 2 teaspoons baking powder, and 1/4 teaspoon salt until no lumps remain.

Whisk the wet ingredients: In another bowl, whisk 3 large eggs, 1/3 cup unsweetened almond milk, 1/3 cup melted butter or coconut oil, and 1 1/2 teaspoons vanilla extract. Add 1 teaspoon lemon zest if using.

Combine: Pour the wet mixture into the dry ingredients and stir with a spatula until just combined. The batter will be thicker than standard muffin batter—this is normal.

Fold in blueberries: Gently fold in 3/4 to 1 cup blueberries. If using frozen, add them straight from the freezer to avoid streaking and do not thaw.

Portion: Divide the batter evenly among the muffin cups. If you like, sprinkle a tiny pinch of granulated keto sweetener on top for a bakery-style finish.

Bake: Bake 20–25 minutes, or until the tops are set and lightly golden and a toothpick comes out clean or with a few moist crumbs. Start checking at 18 minutes.

Cool: Let the muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely. They firm up as they cool.

Enjoy: Serve warm or at room temperature. They’re fantastic with a pat of butter.