Marzipan is a mixture of almonds, sugar, and sometimes egg whites. Its soft, pliable texture makes it ideal for sculpting and decorations. It's available in the baking aisle of supermarkets.
Tint marzipan with orange and red food coloring, a drop at a time, to reach desired color. Divide into 12 pieces. (Cover with plastic wrap when not using.) Shape each piece into a ball, then roll into logs, tapering 1 end, to resemble carrots.
Dip a paring knife into cocoa powder. Make tiny indentations in each carrot with cocoa-dusted knife to evoke the vegetable's texture. Carrots will keep, covered, for up to 1 week. Push fronds into top of each carrot before serving.