Start by setting your oven to 375°F. While that reaches the right temperature, take a standard 12-cup muffin tin and line it with paper liners.
In a large mixing bowl, combine the flour, sugar, baking powder, baking soda, and salt. Use a whisk to stir these together for about thirty seconds to make sure there are no large lumps of flour or soda.
In a separate medium bowl, beat the eggs lightly with a fork. Stir in the Greek yogurt, melted butter, milk, and vanilla extract. Use a sturdy whisk to blend these until the mixture is completely smooth and the yogurt has fully integrated with the eggs.
Make a small hole in the center of your dry ingredients and pour the wet mixture right into the middle. Use a spatula to fold the two together using a gentle circular motion. Stop as soon as you see that the last streaks of dry flour have disappeared.
If you are adding blueberries, raspberries, or chocolate chips, toss them into the bowl now. Use the spatula to give the batter two or three more gentle folds to distribute the mix-ins.
Use a large spoon or a spring-loaded ice cream scoop to divide the batter evenly among the 12 muffin cups. Each cup should be about three-quarters of the way full.
Place the muffin tin on the center rack of your oven and bake for 18 to 22 minutes. You will know they are done when the tops are a light golden brown and feel springy to the touch.
Let the muffins sit in the tin for about five minutes after you take them out of the oven.
