Preheat oven to 350F and line 8 muffin cups with parchment liners (or grease muffin cups very well).
Add yogurt, butter, sweetener, vanilla and apple cider vinegar to a blender. Then add almond flour, baking soda, and salt on top. Blend on low for 10 to 15 seconds until combined.
Add eggs and blend on low for another 15 to 20 seconds, then blend on high for 20 to 30 seconds, until eggs are just incorporated into the batter.
Add all but 2 tablespoon of the frozen berries to blender and stir in by hand (do not blend!). Divide batter among prepared muffin cups and then place a few remaining berries in the top of each.
Bake 15 to 18 minutes, until slightly golden brown and a tester inserted in the center comes out clean. Remove and let cool in pan for a few minutes, then transfer to a wire rack to cool completely.
Serves 8. Each serving has 7.9 g of carbs and 3.29 g of fiber. Total NET CARBS = 4.61 g.Food energy: 211kcal Saturated fatty acids: 3.61g Total fat: 17.09g Calories from fat: 153 Cholesterol: 79mg Carbohydrate: 7.90g Total dietary fiber: 3.29g Protein: 8.28g Sodium: 218mg