Melt dark chocolate candy in the microwave, in 30 second intervals on 50% power. Stir after each heating. Repeat until completely melted. Dip Fudge Stripe Cookies into chocolate, coating completely. Shake off any excess. Set on parchment paper, top side down, until candy coating is completely set.
Using a toothpick, dip marshmallow into chocolate and coat almost entirely. Shake off any excess. Set on parchment paper, until candy coating is completely set. Remove toothpick.
Melt green candy just as you did the chocolate. Flip marshmallow upside down and insert new toothpick in top. Dip into green candy, just barely, to create a small band of green around the bottom.
Coat green candy band with sprinkles or sparkles. Shake off excess.
Place marshmallow in center of chocolate covered cookie. Carefully remove toothpick. Touch up the toothpick hole with a small dab of melted chocolate, if desired.
Spoon some of the remaining melted green candy into a piping bag, ziplock bag or squeeze bottle. On parchment paper, make three small dots of candy in the shape of a triangle. Each dot should be about the size of a chocolate chip. Using a toothpick, swirl the three dots together to form a shamrock shape. Swirl the bottom two dots together first, then the top dot. Pull toothpick straight down to form the stem. Before candy hardens, cover with sprinkles or crushed cake sparkles. Once shamrocks have set up, dust off excess sparkle.
To finish the hat, attach a glittering shamrock with a small dab of melted green.
Your finished treats can be stored for several days in an airtight container, at room temperature.