In a large saucepan, melt butter over low heat. Add marshmallows and stir until completely melted. Remove from heat.

Add Rice Krispies cereal to the melted marshmallow mixture and stir until well coated.

Grease a baking sheet or line with parchment paper. Press the mixture into a flat layer. Let cool slightly.

Using a pumpkin-shaped cookie cutter, cut out shapes from the Rice Krispy mixture. Alternatively, you can shape them by hand.

Melt orange candy melts with vegetable shortening according to package directions. Dip each pumpkin shape into the melted candy, letting excess drip off.

Place coated pumpkins on parchment paper to set. Once mostly set, use a toothpick dipped in melted chocolate to draw a stem on top of each pumpkin.

Let the chocolate stems harden completely before serving.