Lemon Blueberry Cupcakes with a Lemon Buttercream Frosting

1 box Pillsbury Lemon Cake mix (and the eggs, oil and water that it calls for plus the...)
Zest of 1 lemon

Blueberry Compote:

1 1/2 c. blueberries
2 Tbs. Agave Nectar
6 Tbs. powdered sugar

Preheat the oven to 350 degrees. Follow the instructions on the back of the cake mix box and combine the ingredients together. Line two muffin tins with paper liners. Pour the batter 3/4 of the way full into the cups. Meanwhile, heat the blueberries and agave nectar on medium heat. Let the blueberries cook down, and when the mixture starts to boil, and there is about the same amount of liquid as blueberries, turn the heat down and stir a few times. Add the powdered sugar and stir together. Let the mixture cool for 5 minutes so that it can thicken slightly. Pour a spoonful on top of each cupcake. Bake the cupcake for the amount directed on the back of the box mix. Let cool fully on a wire rack before frosting.

Lemon buttercream frosting:

1 stick butter, unsalted
1 tsp. grated lemon zest
1 tsp. vanilla
2.5 (+) c. powdered sugar
1/4 c. milk, 1%
1 Tbs. fresh lemon juice

Beat the butter in an electric mixer for 2 minutes on high. Scrape off of the sides of the bowl. On medium speed, mix in the lemon zest and vanilla. Add a cup of the powdered sugar, then the milk, then the remaining powdered sugar on low speed until you reach the consistency you like. Finally, add the fresh lemon juice. I piped them onto the cupcakes, but you can always spread it on also.