Blueberry Cupcakes

Direction :

Make the topping:
Mix together granulated and brown sugars and cinnamon.
Preheat oven, line muffin pan cups, and sift dry ingredients:
Preheat oven to 375 degrees with rack in upper third of oven. Line cups of a standard muffin tin with baking cups. Sift together flour, baking soda, baking powder, and salt.
Cream butter and sugar:
Beat together butter and granulated sugar with a mixer on medium-high speed until pale and fluffy, 2 to 3 minutes.
Add eggs, one at a time, and vanilla:
Beat in eggs, 1 at a time, then beat in vanilla, scraping down sides of bowl.
Add flour and sour cream, in three additions:
Reduce speed to low, and beat in flour mixture in 3 additions, alternating with sour cream and beginning and ending with flour.
Add berries:
Fold in blueberries.
Divide batter between muffin cups:
Divide batter among baking cups. Add topping, pressing to adhere to batter.
Bake and cool:
Bake until golden and a toothpick inserted in center comes out with moist crumbs attached, 20 to 21 minutes. Remove cupcakes from tin, and let cool completely on a wire rack.
Combine butter and cream cheese for frosting:
Beat together butter and cream cheese with a mixer on medium-high speed until pale and fluffy, about 2 minutes.
Add vanilla and confectioners' sugar:
Reduce speed to low, and gradually beat in vanilla and confectioners' sugar. Raise speed to medium-high, and beat 1 minute.
Add jam and spoon into pastry bag:
Spoon jam on top of icing, and without stirring, spoon icing into a disposable pastry bag.
Pipe frosting:
Snip off a 3/4-inch opening in tip, and pipe swirled mounds of icing on top of each cupcake.