Preheat the oven to 350ºF and prepare a large muffin tin with paper liners or butter/cooking spray.
In the bowl of a stand mixer with the paddle attachment, cream the butter and sugar together until fluffy.
Add in the eggs, oil, and vanilla, mixing thoroughly until combined.
In a separate bowl, mix the flour, baking powder, and salt together.
Alternate adding the dry ingredients and the milk to the wet ingredients, mixing to incorporate after each addition until fully combined.
Fold in the raspberries, lemon juice, and optional lemon zest until just combined.
Using a cookie scoop for even measuring, divide the muffin batter between each muffin tin. If desired, sprinkle some coarse sugar on top before baking.
Bake muffins for about 35 minutes, until golden brown and a toothpick comes out clean.
Serve warm with butter or jam!