Tint marzipan with orange and red food coloring, a drop at a time, to reach desired color.
Divide the tinted marzipan into 12 pieces (cover with plastic wrap or place into a zip baggie when not using). Shape each piece into a ball, then roll into logs, tapering 1 end, to resemble carrots.
Dampen the edge of a paring knife and dip into cocoa powder. Make tiny indentations in each carrot with cocoa powdered knife edge to create texture that resembles a real carrot (the cocoa adds a dirt feel to it).
Carrots will keep, covered, for up to 1 week. When ready to use, cut a slit into the end of each carrot and slip in a carrot frond. Gently push closed to hold together.
Use carrots to decorate cupcakes, cakes, cheesecake, mini-cheesecakes and other pastries.
Notes
Marzipan can be found in the baking aisle of most supermarkets.
Gel-paste food coloring can be found at craft and baking stores. It's much easier to work with than regular food coloring and you need only a little to result in bold colors.
You may also cut marks into the carrots and then brush on a bit of cocoa powder with a small paintbrush.