Preheat and prep: Heat your oven to 350°F (175°C). Line a 12-cup muffin pan with liners. Lightly spray the liners for easy release.

Mix dry ingredients: In a large bowl, whisk 2 cups almond flour, 2 tablespoons coconut flour, 2 teaspoons baking powder, 1/4 teaspoon salt, and 1/2 teaspoon cinnamon (if using).

Whisk wet ingredients: In a separate bowl or measuring cup, whisk 3 large eggs, 1/3 cup melted butter or oil, 1/2 cup sweetener, 1/2 cup unsweetened almond milk, and 1 1/2 teaspoons vanilla. Add 1 teaspoon lemon zest if you like.

Combine: Pour the wet ingredients into the dry. Stir with a spatula until just combined. The batter will be thick but scoopable. If it seems too thick, add 1–2 tablespoons more almond milk.

Fold in berries: Gently fold in 1 to 1 1/4 cups blackberries. If the berries are very large, cut them in half to distribute more evenly. Don’t overmix or the batter will turn purple and streaky.

Fill the pan: Divide the batter evenly among the 12 liners, filling each about 3/4 full. For a bakery look, press an extra blackberry on top of each muffin.

Bake: Bake for 18–22 minutes, or until the tops are set and a toothpick comes out with a few moist crumbs. The edges should be lightly golden.

Cool: Let the muffins cool in the pan for 10 minutes, then transfer to a rack. They firm up as they cool, so resist cutting in right away.

Sweet finish (optional): Dust with a pinch of powdered keto sweetener or brush with melted butter for shine.