Divide the batter evenly among the muffin cups, filling each about ⅔ full.
Sprinkle sugar evenly over the tops of the muffins for a sweet, crunchy topping.
Bake in the preheated oven at 190°C / 374°F (for a regular oven) or 170°C / 338°F (for a fan-assisted oven) for 18-20 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Allow the muffins to cool in the tin for about 5 minutes, then transfer to a wire rack to cool completely.
Serve and enjoy your raspberry muffins warm or at room temperature!
Notes
Room Temperature Ingredients: Make sure the egg and kefir are at room temperature. This helps them mix better and makes the batter more consistent. Mixing the Batter: Be careful not to overmix the batter. Overmixing can make the muffins tough. Just mix until the dry ingredients are moistened and the batter is slightly lumpy.Folding in Raspberries: Gently fold in the raspberries to avoid crushing them. This will help spread them evenly through the muffins and keep their shape.Uniform Size: Use an ice cream scoop to evenly portion the batter into the muffin cups. This way, the muffins will all be the same size and bake evenly.Filling the Muffin Cups: Fill the muffin cups about two-thirds full so the muffins have room to rise without spilling over.Storing Muffins: Keep the muffins in an airtight container at room temperature for up to 2 days. If you need to store them longer, put them in the refrigerator for up to a week or freeze them for up to 3 months.