Preheat the oven to 375 degrees. Add butter and sugar in a medium bowl and beat until smooth. One at a time, add each eggs blending in between.
Mix in vanilla. In a separate bowl, whisk together flour, salt, cinnamon, and baking powder. Add to sugar mixture, a little bit at a time, alternating with the 1/2 cup of milk.
Fold in the blueberries and raspberries.
Divide batter among 12 muffin tins lined with parchment paper cupcake liners. Sprinkle sanding sugar over the tops and bake at 375 degrees for about 15-20 minutes or until the centers are finished.