Melt the butter in a large saucepan over medium heat. Add the marshmallows and stir until fully melted and smooth.
Divide the melted marshmallow mixture into two equal portions in separate bowls. Stir black gel food coloring into one portion until the color is even. Stir orange gel food coloring into the second portion until the color is even.
Mix 3 cups of Rice Krispies cereal into the black marshmallow mixture until coated. Press this layer firmly into the bottom of a greased 8x8 pan to form the brim.
Mix the remaining 3 cups of Rice Krispies cereal into the orange marshmallow mixture until coated. Spread and press this layer evenly on top of the black layer.
Melt the chocolate chips in a microwave-safe bowl in 20-second bursts, stirring between each until smooth. Spread the melted chocolate over the top orange layer in a pointed triangle shape to create the hat crown.
Scatter the green sprinkles over the chocolate while it is still soft. Let the pan cool at room temperature for 30 minutes before slicing into four hat-shaped pieces.