Preheat Oven and Prepare Pans: Preheat your oven to 375°F. Line a muffin tin with paper liners or lightly grease with butter.
Mix Dry Ingredients: In a large bowl, whisk together the all-purpose flour, whole wheat flour, granulated sugar, baking powder, and salt. This mix is key to a light and tender texture.
Combine Wet Ingredients: In another bowl, beat the eggs lightly. Then, whisk in the melted butter, milk, vanilla extract, lemon juice, and lemon zest. This blend adds moisture and a fresh, tangy kick.
Mix Batter: Slowly add the wet ingredients to the dry ingredients, stirring gently until just combined. Take care not to overbeat the mixture; leaving a few lumps is completely acceptable.
Fold in Raspberries: Gently fold the raspberries into the batter, taking care to keep them whole. This step ensures each muffin bursts with fruity flavor.
Fill Muffin Cups: Using a spoon, transfer the batter into each muffin cup, filling them roughly two-thirds of the way. This allows room for the muffins to rise evenly.
Bake: Place the muffin tin in the preheated oven and bake for 18 to 22 minutes, or until a toothpick inserted into the center comes out spotless. Keep an eye on them towards the end of baking to avoid overbaking.
Cool and Serve: Move the muffins onto a wire rack so they can cool thoroughly. Then, transfer to a wire rack to cool completely. Enjoy them warm or at room temperature.