01 - Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners or lightly grease with butter or oil.
02 - In a large bowl, whisk together ricotta, milk, oil, eggs, vanilla, lemon zest, and lemon juice until smooth and well incorporated.
03 - In a separate medium bowl, whisk together flour, sugar, baking powder, baking soda, and salt until evenly distributed.
04 - Add the dry mixture to the wet mixture and stir gently with a spatula until just combined. Do not overmix.
05 - Gently fold in the raspberries, being careful not to break them apart. A few streaks of flour are fine.
06 - Divide the batter evenly among the prepared muffin cups. Sprinkle tops with coarse sugar for a crunchy finish, if desired.
07 - Bake for 20 to 24 minutes, or until a toothpick inserted in the center of a muffin comes out clean.
08 - Let cool in the pan for 5 minutes, then transfer muffins to a wire rack to cool completely.