1/2 cup yellow candy-coated chocolates, such as Sixlets or M&M's
Prepare cake mix according to package directions. Pour batter into greased 9"x13" pan lined with wax paper and smooth with spatula. Bake until firm. Cool and invert.
To make the letter detail, press 20 red spice drops together. Sprinkle a clean work surface with red decorating sugar and roll out the candies to a 4 1/2"x 5" rectangle, adding more red sugar to prevent sticking. Make a template of your child's initial with cardstock; place it on top of rolled candy. Cut out letter with a paring knife; reserve scraps.
To make red shield border, unroll the fruit leather and press two strips together to make it doubly thick. Roll one side of the strip in red sugar to coat. Cut into two 11" strips, two 4" strips and one 9" strip. Cut the scraps into six 1/2" triangles.
To make blue circle, press 28 white spice drops together. Sprinkle a clean work surface with blue decorating sugar. Roll candies to a roughly 6 1/2" circle, adding sugar to prevent sticking. Trim circle with a paring knife.
To make yellow bolts, press 12 yellow spice drops together. Sprinkle a clean work surface with yellow decorating sugar and roll out candies to a 3"x 4" rectangle, adding more yellow sugar to prevent sticking. Cut out bolts with a paring knife.
Place cake on work surface, trimming top with a serrated knife to make level. Transfer cake, flat side down, to a serving platter. Cut cake according to the chart (below) and rearrange pieces to form shield.
Spread thin layer of frosting over cake. Place in freezer for 20 minutes.
Spread remaining frosting over cake. Place blue candy circle in the center. Arrange red strips along edge of cake, trimming ends with scissors when necessary. Add yellow candies around blue circle. Place red letter and small red triangles in center of blue circle and yellow bolts on either side of letter