In the bowl of a stand mixer fitted with the paddle attachment, cream together the sugar and the butter until light and fluffy. Add in the egg and vanilla and continue mixing until everything is well combined.

In a medium-sized bowl, combine the flour, salt, sage, and baking soda and mix to combine. Add the flour mixture to the creamed mixture, a little at a time, with the mixer running on low. Continue mixing until everything is combined into a smooth dough ball. Refrigerate the dough for 20 minutes if it seems a bit sticky, or just use it immediately.

With a small cookie scoop, scoop out the dough, roll it into little dough balls, and place them on a parchment-lined baking pan. Using the handle of a wooden spoon or your thumb, create a small indent in the top of each dough ball, then fill it with about 1/2 teaspoon of apple butter.

Bake the cookies at 350° for 12 minutes, turning the cookie sheet halfway through the baking time. Allow the cookies to cool completely on a wire cooling rack.

Once the cookies are cooled, prepare the glaze, then drizzle it over each cookie in a zig-zag pattern. Allow the icing glaze to set for about 20 minutes before storing the cookies in an airtight container.