Blueberry Lime Cake (or Cupcakes)

 based on this recipe for Blackberry Lime Cupcakes
https://cookienameddesire.com/blackberry-lime-cupcakes-with-lime-frosting/

Ingredients

For blueberry jam

• 1 cup blueberries
• 1/3 cups sugar
• juice of 1 lime

For Cupcakes

• 1½ cups all-purpose flour
• 1½ teaspoon baking powder
• ½ teaspoon salt
• zest of 3 limes
• 1 stick unsalted butter, room temperature
• 1/2 cup sugar
• 1 teaspoon vanilla extract
• 3 large eggs, room temperature
• ½ cup buttermilk, room temperature

For Frosting

• 1 stick unsalted butter, room temperature
• 2 1/2 cups powdered sugar
• 1/2 cup blueberry jam
• 1 cup fresh blueberries for decorating top of cake (if desired)

Instructions

Make the Jam

1. Mix the blueberries and sugar together in a small saucepan and heat on medium-high until the berries break down and the juiced become thick and syrupy. Set aside to cool.

Make the Cupcakes

1. Preheat the oven to 350 degrees F. Spray 13x9 pan with cooking spray or Line a muffin tin with cupcake liners (makes 12 cupcakes).
2. Mix together the flour, baking powder, lime zest, and salt together in a medium bowl and set aside.
3. In a mixer, beat together the butter and sugar until light and fluffy.
4. Beat in extract and the eggs one at a time, mixing well between each egg and beating for one additional minute after the last egg.
5. Alternate between adding the flour and the buttermilk, beginning and ending with the flour. Mix until just combined.
6. Evenly distribute the batter in the cake pan or among the cupcake liners. Spoon a heaping half cup of  jam over the cake batter (or heaping teaspoon of jam over the cupcake batter) and swirl in using a skewer or knife.
7. Bake for about 35 minutes (17 - 20 minutes for cupcakes), or until a light golden brown and the tops spring back when gently pressed upon. Take out the oven and allow to cool completely.

Make the Frosting.

1. Beat the butter until smooth and cream. Beat in the powdered sugar one cup at a time. Mix in the jam and beat well. 

Assembly

1. Spread frosting over cake & sprinkle with fresh blueberries if desired.  For cupcakes, fit a piping bag with a large open star tip and fill with the frosting. Frost each cupcake.  Top with a few fresh blueberries if desired. 
2. Cupcakes make last up to five days in refrigerator.