Preheat the oven to 400°F. You will need an unlined, un-greased non-stick cookie sheet for the spritz cookies to properly release from the cookie press.
In the bowl of a stand mixer beat butter and sugar until light and fluffy, about 3 minutes.
Add egg yolk and yogurt; mix until fully combined. Add vanilla extract and orange zest and mix until incorporated. (It may look slightly curdled, and that's ok.)
Add flour, baking powder, and salt to the mixture and mix until a soft dough forms and everything is fully combined.
Scoop the dough into the cookie press with your chosen disc. (I used the wreath design.) Pump the press a few times to get the dough going, then press cookies onto the ungreased cookie sheet.
Bake for about 7 minutes or until the edges become a light golden color. Remove from oven and cool completely.
Meanwhile, melt the chocolate until smooth. Line another pan or the counter top with a sheet of parchment paper.
When the cookies have cooled completely, dip each cookie half way into the chocolate, letting the excess drip off. Place cookies onto parchment paper and allow to set before serving or packaging. (You can speed this up by placing them in the refrigerator or freezer for a few minutes if desired.)