Preheat the oven to 350 degrees. Line baking sheet with parchment paper or silicone mats. Set aside.
In a large bowl, using an electric mixer cream butter and granulated sugar on high for about 30 seconds to 1 minute. Beat until the mixture is fluffy and light in color.
In a small bowl add the egg, vanilla, baking powder, and salt. Add this entire mixture to the butter and beat on medium speed for about 30 seconds until well mixed.
Add the flour 1 cup at a time to the wet ingredients and beat with your mixer on low speed. Gradually add the remainder of the flour until all is incorporated. Make sure to scrape down the sides of the bowl as you go. The dough will be slightly dry at this point.
Pour the heavy cream into the dough and beat on high speed for 10-15 seconds until the dough moistens and comes together.
To prevent the cookie dough from drying out, wrap in plastic wrap or cover the bowl in plastic wrap if you are baking immediately.
Take about half of your cookie dough and place on a piece of wax paper. Shape the dough into a long, log shape.
Place another piece of wax paper on top of the dough log and roll out the cookie dough to approximately ¼" in thickness.
Place rolled dough in the freezer for 10-15 minutes or until it is firm, but not frozen solid.
Cut out Halloween shapes and place on a prepared baking sheet. Baking time will range from 11-14 minutes or until the outer edge of cookies are a light golden brown color.
Let cool on a cookie sheet for about 5 minutes before transferring to a wire rack to cool completely.
Do not decorate cookies until they are completely cool for at least several hours.
Make the royal icing using this recipe! Dye the icing into different colors including white, orange, purple, and black. You will need a flood consistency and a detail consistency for white, orange, and purple.
Decorating the Pumpkin: With the orange detail consistency icing, outline the pumpkin and add 2 curved lines up the middle creating the shape of the pumpkin. Fill in the middle section of the pumpkin with the orange flood icing. Allow the center section to slightly dry, the top should appear less shiny (10-15 minutes) and then fill in the flood in the 2 outside pieces. With the black detail icing, pipe the stem of the pumpkin. Allow cookie to dry for 8 hours up to overnight. Using the edible marker, create eyes and smile. Mix pink luster dust with a few drops of water or vodka and using a food-safe brush, add blush cheeks.
Decorating the Ghost: With the white detail icing, outline the ghost. Fill in the center with flood white icing and allow to dry for 8 hours or overnight. With the edible marker, add the eyes, mouth, and the "boo! message. Using the same pink luster dust mixture as with the pumpkins, add blush cheeks.
Decorating the Bat: With the purple detail consistency icing, outline the center portion (the body) of the bat. Continue with the detail consistency icing and outline the wings. Fill in the body of the bat with the flood purple icing and let it slightly dry (at least 10-15 minutes) before filling in the wings with the purple icing. Let the cookie dry at least 8 hours or overnight. Once dry, add the eyes and mouth with edible marker and add accents to the wings.
For step by step pictures, see the pictures in the blog post!