Put the chocolate in a small bowl and dip the top of your glass in it. Stick the pretzels around the rim. Line the inside and outside of the glass with generous squeezes of chocolate syrup. Pour in the milkshake then top with enough whipped cream to fill the glass.
Stick the doughnut directly on top, then a cupcake threaded through a wooden skewer. Add a chocolate straw and sprinkle over the caramel popcorn. Finish with a generous drizzle of caramel syrup. To serve add a straw and a sparkler.