Preheat your oven to 375°F (190°C). Line a 12-cup muffin tin with paper liners or lightly grease. Rookie mistake: don’t skip preheating!
Mix dry ingredients. In a large bowl, whisk flour, sugar, baking powder, baking soda, and salt until evenly combined.
Prepare the berries. Toss raspberries with a teaspoon of flour to prevent them from sinking. Set aside.
Mix wet ingredients. In another bowl, whisk together egg, Greek yogurt, milk, melted butter, and vanilla until smooth.
Combine wet and dry. Pour wet into dry and fold gently. Do not overmix! The batter should be slightly lumpy. Overmixing = tough muffins.
Add berries. Gently fold raspberries into the batter. Don’t smash them—this is not jam yet.
Fill the muffin cups. Spoon batter into prepared cups, about ¾ full each.
Bake. 20–25 minutes or until tops are golden and a toothpick comes out clean.
Cool. Let muffins sit for 5 minutes in the tin, then transfer to a wire rack. Try not to eat them all in one sitting… okay, no promises.