Preheat the oven to 375 degrees. Line a baking sheet with parchment or a non stick baking mat.
Place the butter, cream cheese and sugar in the bowl of a mixer. Beat until smooth, about 3 minutes.
Add the egg yolk and vanilla, beat until combined.
Add the flour and mix until just blended.
Divide the dough in half. Color half the dough green if desired.
Shape 1/4 of the dough into a log and place into the barrel of the cookie press.
Spritz the cookies directly onto the baking sheet, about 1 inch apart.
Bake for 10-12 minutes or until cookies are set and light golden brown on the edges.
Cool on the pan for 5 minutes, then transfer to a cooling rack. Repeat the process with the remaining dough.
After all cookies have cooled, place the dark and white candy melts into two bowls. Microwave one bowl at a time in 30 second increments until melted, stir until smooth.
Dip the cookies halfway into the chocolate and decorate with sprinkles. If the dipping chocolate starts to harden, microwave for a few seconds to re-melt.
Let dry completely, then serve, or store in an airtight container for up to 3 days.