Preheat the oven to 350 degrees. Line 2 baking sheets with parchment paper or silicone lined baking mat.
In a large mixing bowl, cream together the butter, sugar, and vanilla until light and fluffy, about 3-5 minutes. Add the egg and beat until combined.
Add the bread flour and salt, beat until combined and the dough should form a ball.
Remove 1 cup of the dough and set aside. With the remaining dough, add in 1 teaspoon green food coloring, adding more if needed for the desired shade of green.
From the green cookie dough, make 1 (1-inch) ball and 5 (1/2-inch) balls. From the plain cookie dough, make 1 (3/4 inch) ball and 5 (1/4-inch) balls. You will have a body, head, hat, four green arms and four white hands and a green ball for the top hat. It makes the most sense to make all the parts for the Leprechauns first, then assemble.
On your prepared baking sheet, place the green 1-inch ball, gently flatten until 1/2 inch thick. Attach four of the green 1/2-inch balls for arms and legs. Next, attach the plain 3/4-inch ball for a head, gently flatten until 1/2 inch thick.
Attach the plain 1/4-inch balls for the Leprechaun's hands and feet.
Shape the remaining green 1/2-inch ball into a square and skinny oval (shape it into a top hat) and attach it. Repeat with remaining dough, arranging the cookies 2 inches apart on the baking sheet. Add mini chocolate chips for eyes and buttons (see above photos for reference!).
Transfer to the oven and bake the Leprechauns for 12-15 minutes, until the white dough gets lightly golden
Frosting (if making from scratch): Add the butter to the bowl of a stand mixer and whip until extra light and fluffy, about 2-3 minutes. Add the powdered sugar and vanilla. Beat together until whipped, approx. 2 additional minutes.
Add orange food coloring to get your desired shade of orange (if not using pre-made, already dyed orange frosting).
To decorate: Transfer the frosting to a piping bag fitted with a small tip. Or, take a ziplock bag and snip a very small portion of the corner off the bag and preferably use the small tip with the bag. Use the bag to go around each Leprechaun's face to create the beard and mustache. Enjoy!