01 - Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners or lightly grease each cup with butter or oil.
02 - In a large mixing bowl, whisk together the ricotta cheese, whole milk, vegetable oil, eggs, vanilla extract, lemon zest, and lemon juice until smooth and well blended.
03 - In a separate medium bowl, whisk together the all-purpose flour, granulated sugar, baking powder, baking soda, and salt until evenly distributed.
04 - Pour the dry ingredient mixture into the wet ingredients. Stir gently with a spatula until just combined. Avoid overmixing to keep the muffins tender.
05 - Gently fold the raspberries into the batter using a spatula, taking care not to crush the berries and streak the batter with juice.
06 - Divide the batter evenly among the prepared muffin cups, filling each about three-quarters full. Sprinkle the tops with coarse sugar if desired for a crunchy finish.
07 - Bake for 20 to 24 minutes, or until a toothpick inserted into the center of a muffin comes out clean and the tops are lightly golden.
08 - Allow the muffins to cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely before serving.