Sift together the ★ ingredients. Bring butter, egg and milk to room temperature.
In a bowl, add butter and beat until soft. Add sugar little by little and beat until fluffy.
Slowly add the beaten egg and whisk well.
Add flour in three batches, alternating with milk (flour-milk-flour-milk-flour.) Combine lightly using a rubber spatula. Add the blueberries.
Spoon the batter into the muffin cups and top with more blueberries if desired. Bake in a 180℃ oven for 25~30 minutes.
You can definitely use fresh blueberries. Raspberries may be good also. If you don't have berries, make plain muffins.
Story Behind this Recipe
I have been trying to create muffins that won't harden when cooled. It took me about a year. I looked up many different recipes and finally came up with this one. I use this recipe to make muffins in many different flavors.
The point is to stop mixing right after the flour is incorporated with wet ingredients in Step 4! This keeps the muffins soft even when cold.