Melt butter in a large saucepan over low heat.

Add marshmallows and stir until completely melted and smooth.

Stir in food coloring until desired shade is reached.

Remove from heat and quickly fold in Rice Krispies cereal until evenly coated.

Press mixture into a greased 9x13-inch pan, using a spatula or wax paper to flatten evenly.

While still slightly warm, sprinkle with Halloween sprinkles and gently press them in.

Cut into squares or shapes once cooled.

Decorate with candy eyes and drizzle with melted chocolate or candy melts if desired.