Preheat oven to 350 degrees F. Line a muffin tin with liners.

In a large bowl, combine flour, brown sugar, baking powder, soda and salt. Stir to combine. Mix in lemon zest. Add mascarpone cheese and mix in with a fork, stirring until crumbly, evenly dispersed and covered in flour. In a small bowl, whisk together milk, yogurt, egg, vanilla extract and butter. Add the wet ingredients to the dry, stirring until just combined and wet.

Use a 1/4 cup measure or ice cream scoop to fill the muffin liners 2/3 of the wall full. Bake for 15-17 minutes, until tops are set and golden. Remove and let cool slightly before serving.