Start out by preheating your oven to 400 degrees F. Line a regular-sized muffin pan with paper or silicone muffin liners. This should make approximately 18 muffins.
Next work in the softened butter with your electric mixer. The mixture will sort of resemble coarse sand.
Now blend in the eggs, milk, and vanilla until all ingredients are combined, but being careful not to overbeat the mixture.
Gently fold in the raspberries.
Sprinkle a little sparkling sugar on top of the batter, if desired.
Bake the muffins for 20 to 25 minutes or a toothpick comes out clean.
These muffins aren't overly sweet! The flavor of fresh raspberries shines through!
Serving size is 2 muffins.