Vanilla Cupcakes with Lemon-Lime Curd Filling and Lemon-Lime Frosting

VANILLA CUPCAKES
1 cup (2 sticks) unsalted butter, room temperature
2 cups sugar
4 large eggs, room temperature
2-3/4 cups all-purpose flour
1 teaspoon baking powder
1 teaspoon baking soda
1/8 teaspoon salt
1 cup milk
1 teaspoon vanilla

1. Beat butter on high until soft, about 30 seconds.
2. Add sugar. Beat on medium-high until light and fluffy, about 3 minutes.
3. Add eggs one at a time, beat for 30 seconds between each.
4. Whisk together flour, baking powder, and baking soda in a bowl.
5. Measure out milk and vanilla together.
6. Add about a fourth of the flour to the butter/sugar mixture and beat to combine.
7. Add about one third the milk/vanilla mixture and beat until combined.
8. Repeat above, alternating flour and milk and ending with the flour mixture.
9. Scoop into cupcake papers about half to three-quarters full (depending on whether you want flat or domed cupcakes).
10. Bake for 22-25 minutes at 350 degrees F until a cake tester comes out clean.

LEMON-LIME CURD
1/2 cup fresh lemon juice
1/4 cup fresh lime juice
1 tbsp finely grated lemon zest
1 tbsp finely grated lime zest
3/4 cup sugar
3 large eggs
1 stick (1/2 cup) unsalted butter, room temperature

1. In a medium saucepan, whisk together the lemon juice, lime juice, lemon zest, lime zest, sugar and eggs. Cut the butter into bits and add it to the saucepan.

2. Turn on the heat to medium-low and cook the mixture gently, whisking constantly, until it thickens up enough to hold the marks of the whisk and is just about to come to a simmer. This takes me usually around 20-25 minutes — better to be gentle than to curdle your eggs. The end mixture will be a buttery, creamy light yellow.

3. Remove from the heat and place into a bowl to cool. Strain it if you want to get rid of the zest. Place a piece of plastic wrap on the surface of the curd to prevent a skin from forming as it cools. Store the curd in the fridge.

LEMON-LIME FROSTING
½ cup butter, softened
4 cups confectioner’s (icing) sugar
2 tbsp fresh lemon juice
1 tbsp fresh lime juice
¼ cup light (10%) cream

1. Beat together all ingredients until smooth and creamy (I had to add some extra lemon juice to bring it to a spreadable consistency)

TO ASSEMBLE CUPCAKES
1. Using a small pairing knife, cut off the top of the cupcake in the shape of a cone. Flip the top over and cut off the cone.
2. Fill the cavity with a teaspoon or so of curd.
3. Replace top.
4. Frost with frosting.