Cream the room temperature butter using a whisk or mixer until it turns slightly pale.

Add sugar to the creamed butter and mix until partially dissolved.

Gradually add the egg in four parts, mixing well each time.

If the mixture separates, gently warm it using a double boiler while stirring to recover consistency.

Sift all dry ingredients and mix them into the butter mixture. Adjust the consistency with milk.

Fill muffin molds to 70% capacity and bake at 170°C for 20–25 minutes.

Check doneness by inserting a chopstick into the cracks; if it comes out clean, the muffins are ready.