Blueberry Balsamic Cupcakes

I topped some of my cupcakes with pastry scraps from another failed project. I liked the look, but they aren't a necessary decoration.

Lovely Yellow Cake slightly adapted from Pick Yin (via Smitten Kitchen)
This is now my absolute favorite yellow cake recipe. It's moist and light - but still somewhat dense like a good cake should be. Makes about a dozen cupcakes.

2 c + 1 Tbsp (284 g) cake flour
1/4 c (23 g) powdered milk
1 tsp baking powder
3/4 tsp baking soda
1/2 tsp salt
1/2 c (113 g) butter, room temp
1 c (200 g) sugar
1 tsp vanilla extract
1 egg
2 yolks
1 c (237 ml) buttermilk, room temp (make your own by adding 1 tbsp lemon juice or vinegar to 1 c milk)

Preheat oven to 350F and line a muffin tin. Set aside.

In a small bowl, whisk together the flour, powdered milk, baking powder, baking soda and salt. Set aside.

In a large mixing bowl, cream the butter and sugar for about 5 minutes, until light and fluffy. Scrape down the sides of the bowl, then beat in the vanilla. Scrape down the bowl again and add the egg. Beat about 30 seconds to combine, scrape the bowl, then add the yolks. Beat to combine. Add 1/3 of the flour mixture, mix just to combine and add half of the milk. Continue adding the dry and wet ingredients in this fashion, ending with dry.

Divide batter evenly between the liners and tap on the counter a few times to eliminate large air bubbles. Bake until golden and a wooden pick inserted in center of cake comes out clean, 20-22 minutes. Cool in pans until cool enough to handle, then cool completely on racks.

Blueberry Balsamic Boiled Frosting adapted from Baked: New Frontiers in Baking
I hope you don't mind the vagueness of the jam part. You don't have to be completely accurate - just do what feels right. What is important is to make sure you cook out most of the water or else it will break your buttercream when you try to incorporate it. Otherwise... Enjoy!

1 c blueberries
1 1/4 c (250 g) sugar, divided
1/8 tsp nutmeg
2-4 tbsp balsamic vinegar, to taste
1/3 c (47 g) all-purpose flour
1 1/2 + 1/3 c (233 ml) milk
1 1/2 c (355 g) butter, room temp and cubed
1 tsp vanilla

Combine the blueberries, 1/4 c (50 g) of sugar, nutmeg and balsamic vinegar in a sauce pan. Reduce until most of the liquid is gone. Be sure you taste it and adjust the balsamic vinegar as necessary. You'll want it a little stronger than you might think just so it stands out in the frosting. Set aside to cool.

Combine the sugar and flour in a cool saucepan. Stir in the milk and cream, then set the pan over medium heat. Stirring frequently, cook the mixture until quite thick, 10-15 minutes.

Remove the pan from heat and pour the mixture into the bowl of your mixer. Fit with the paddle attachment and whip on high speed until the outside of the bowl is cool to the touch, about fifteen minutes.

When the bowl is cool, add the butter all at once and whip on high speed until very light and fluffy. Add the vanilla and whip to combine, then add the blueberry balsamic mixture in small amounts, to taste.