Set up your workspace: Line a baking sheet with parchment paper and lightly grease your hands with cooking spray or butter. This keeps the sticky marshmallow mixture from sticking to you while you shape each pumpkin.

Melt the butter: In a large pot over low heat, melt the butter completely, swirling the pan so it coats the bottom evenly, about 1 minute.

Melt the marshmallows: Add the mini marshmallows to the pot and stir constantly over low heat until completely melted and smooth, about 4 minutes. Stir in the vanilla extract at the end.

Fold in the cereal: Remove the pot from heat and add the crispy rice cereal, folding gently with a spatula until every piece is coated in the marshmallow mixture.

Let the mixture cool: Let the mixture sit for 2 to 3 minutes until it's cool enough to touch but still soft and pliable.

Shape into pumpkins: Scoop about 2 tablespoons of mixture, roll into a ball with greased hands, then press light ridges into the sides with your finger to look like a pumpkin. Set each one on the parchment-lined sheet.

Let the shapes set: Let the shaped pumpkins sit at room temperature for about 10 minutes until they hold their shape firmly.

Melt the orange candy melts: Place the orange candy melts in a microwave-safe bowl and heat in 30-second bursts, stirring between each, until smooth and pourable. Stir in the shortening if the mixture seems too thick.

Dip or drizzle each pumpkin: Dip the bottom half of each shaped treat into the melted candy coating, or drizzle it over the top with a spoon, then set back on the parchment paper.

Add pretzel stems: While the coating is still soft, press a small piece of pretzel stick into the top of each pumpkin to form a stem.

Draw simple faces: Once the coating has set, about 10 minutes, use black gel icing to draw simple jack-o'-lantern faces on each pumpkin if desired.

Serve and enjoy: Let the treats fully set for a final 5 minutes before serving or packing them up for a Halloween party.