Preheat the oven to 375 degrees F.
Line each muffin cup with a paper liner. Set aside.
Add the flour, baking powder, and baking soda to a large bowl and whisk together. Set aside.
Place the melted butter and packed brown sugar into the bowl of a stand mixer fitted with a paddle attachment.
Mix on low speed until combined.
Add the egg and mix on low speed until combined.
Add the sour cream to the butter mixture and combine.
Pour in the milk and combine on low speed.
Slowly add in the dry ingredients and mix until just combined. Do not over mix.
Add the raisins. You can use the mixer on low to combine them or you can mix them in with a wooden spoon.
Using a cookie scoop, place a large scoop of dough into each well of the prepared muffin tin. It should almost fill the cup. You can flatten it down a bit with the back of a spoon.
Sprinkle the top of each muffin with sparkling sugar.
Bake for 22-25 minutes until golden brown and a toothpick inserted into the middle comes out clean.
When cool enough to handle, remove the muffins to a wire rack to finish cooling.