1.In a medium bowl, combine cake crumbs and frosting. Using wet hands, shape level tablespoons of mixture into balls, squeezing firmly. Place on a baking paper-lined tray; freeze 1 hour or refrigerate 3 hours or overnight, until firm.
2.In a medium heatproof bowl over a medium saucepan of simmering water, melt white chocolate until smooth (don’t let water touch base of bowl); tint chocolate pale orange. Pour into a heatproof jug.
3.Dip the end of one stick into chocolate, then push it about halfway into a ball of cake. Return to tray. Repeat with remaining sticks and balls of cake. Place tray in the freezer about 5 minutes to set.
4.Meanwhile, cut 22 small triangles from fruit sticks for noses. Cut brown Smarties in half; attach to the top of pops with a little of the chocolate to make ears. Stand upright until set.
5.Dip one cake pop into the chocolate, covering the ears too, rocking back and forth to coat; don’t swirl the pop, or it’ll break. Allow excess chocolate to drip back into the jug. Stand upright in a styrofoam block until set. Repeat with remaining cake pops. Re-melt chocolate as necessary.
6.Cut an edge from each of the remaining Smarties; attach them to pops with a little chocolate for the mane. To make whiskers, attach six vermicelli pieces to each pop; top with fruit stick triangles for a nose. Stand pops upright until set.
7.Make royal icing: Sift the icing sugar through a fine sieve. Lightly beat the egg white in a small ball until mixture is just broken up (do not whip into peaks). Beat in the icing sugar, 1 tbsp at a time, until it reaches desired consistency. Using a wooden spoon, mix in in the lemon juice. Divide into quarters; reserve &3/4; for another use.
8.Tint royal icing black. Spoon icing into a small piping bag fitted with a 3mm tube. Pipe on eyes and mouths.