Step 1

Preheat oven to 350 degrees F. Arrange cupcake liners in three 12-cup muffin pans.

Step 2

For cake: In large bowl, whisk together flour, 1 cup granulated sugar, baking powder, baking soda, and salt. Add oil, 5 egg yolks, lemon juice, lime juice; whisk until well combined.

Step 3

In another large bowl, with mixer on medium-high speed, beat 7 egg whites until foamy. Add cream of tartar; beat until soft peaks form. With mixer running, gradually sprinkle in remaining 1/2 cup granulated sugar. Beat white until stiff peaks form. With rubber spatula, stir in 1/3 of beaten egg whites; gently fold in remaining beaten egg whites.

Step 4

Scoop scant 1/4 cup of batter into each muffin-pan cup. Bake 12 to 15 minutes or until toothpick inserted into centers comes out clean. Cool slightly in pans on wire rack. Transfer cupcakes from pans to wire rack; cool completely.

Step 5

For frosting: In large bowl, with mixer on med. speed, beat mascarpone and heavy cream until combined. Gradually beat in confectioners' sugar, scraping down side of bowl occasionally. Increase speed to medium-high; beat in vanilla until medium peaks form. Refrigerate until ready to use.

Step 6

Fill piping bag with curd; snip tip off of bag. To fill cupcakes, insert tip of piping bag into top of cooled cupcakes. Squeeze about 2 teaspoon curd into center. Repeat with remaining cupcakes.

Step 7

Spread frosting on cupcakes. In shallow dish, place sanding sugar. Roll edges of each cupcake in sugar. Decorate tops with jelly beans. Decorated cupcakes can be refrigerated up to 2 days (allow to come to room temperature before serving).