Prep your pan and oven. Heat the oven to 350°F (175°C). Line a 12-cup muffin pan with paper liners. Lightly spray the liners to prevent sticking.

Whisk the dry ingredients. In a large bowl, combine almond flour, coconut flour, sweetener, baking powder, and salt. Break up any clumps with a whisk for an even batter.

Mix the wet ingredients. In a separate bowl, whisk the eggs, melted butter, vanilla, and sour cream until smooth. If the butter starts to seize, your ingredients may be too cold—just keep whisking.

Combine wet and dry. Pour the wet mixture into the dry ingredients. Stir until just combined. If the batter looks too thick or dry, add almond milk 1 tablespoon at a time until it’s thick but scoopable.

Fold in raspberries. Gently fold in the raspberries. If using frozen berries, add them straight from the freezer and fold carefully to avoid streaking.

Fill the muffin cups. Divide the batter evenly among the 12 cups. The batter will be thick; a cookie scoop works well. Sprinkle a pinch of coarse keto sweetener on top if you like a sparkly finish.

Bake. Bake for 18–22 minutes, or until the tops are set and a toothpick comes out clean or with a few moist crumbs. Avoid overbaking to keep them tender.

Cool. Let muffins cool in the pan for 10 minutes, then transfer to a rack to cool completely. They firm up as they cool, so be patient.