Beat the butter and sugar with an electric mixer until light and fluffy. Add the vanilla extract and eggs and beat until combined. In a separate bowl, combine the flour, baking soda and salt. Add the flour mixture in 2 additions, alternating with the sour cream.
Spoon the mixture into a muffin pan lined with muffin liners. Bake at 350F for 20 minutes, or a skewer inserted into the cupcakes comes out clean. Cool completely.
Crumble the cupcakes into a fine crumb. Add the vanilla frosting and mix well – the mixture should be sticky and easily molded into shapes.
Divide the mixture into 20 balls, then gently shape into the shark’s body, similar to a teardrop shape.
Using a sharp knife, slice 1 cup of white candy melts into long, pointed pieces. You will need 5 pieces per truffle.
Stick one piece into the top of the truffles for the classic shark fin, two into the sides as the side fins, then two into the back as the tail.
Place the truffles onto a small baking sheet lined with plastic wrap and place in the freezer for 30 minutes, or until firm.
Combine the remaining white and black candy melts in a bowl – the addition of a few black candy melts will make it grey! Microwave the candy melts for 30 second intervals, or until fully melted.
Add the melted vegetable shortening and mix until combined. This will give the candy melts a thinner consistency and it will coat the truffles much more evenly. Allow the candy melts to slightly cool, until it is just warm.
Place a truffle on a fork and lower into the candy melts, fully coating it. Tap the fork on the side of the bowl to remove any excess candy melts, then return the truffle to the baking sheet.
Immediately stick 2 mini chocolate chips onto the truffle as the eyes – this should be done before the candy melts have set, so you will need to move quickly and do this after dunking each truffle.
Repeat with the remaining truffles, then transfer the baking sheet to the freezer for the candy melts to fully harden, about 15 minutes.