Whisk the flour, baking powder and salt together in a medium bowl and set aside.
Using a mixer, beat butter and sugar together until light and fluffy in a large bowl. Add in the egg and vanilla and combine. Stir in your dry ingredients from the medium bowl.
Shape dough into a flattened ball and wrap in plastic wrap. Refrigerate the dough about an hour, or until chilled.
Preheat the oven to 325F/163C, while preheating, line 2 baking sheets with parchment paper and set aside.
Lightly flour a clean surface and roll out your chilled dough to a quarter-inch thick. Using a cookie cutter, cut out 3” rounds and place on your lined baking sheets. Freeze for 30 minutes.
Bake cookies 16-18 minutes, or until edges are a light golden color. Let cool completely.
While cookies are cooling, make icing by stirring together powdered sugar, corn syrup and milk until smooth. Add milk in small increments to thin if necessary.
Using a spoon, frost each cookie with about 1 Tablespoon of icing. Use the back of the spoon to smooth the icing in an even, smooth circle.
Using your black decorating gel, draw you thin lines across the cookies to create a string of lights. Immediately add your M&Ms on the black line to create the colored lights. Let cookies dry and set.
Notes
Recipe slightly adapted from Delish.
If you don't have mini M&M’s, you can use the regular size or swap in other colored candies.
For even easier Christmas cookies, skip the baking from scratch and use a store-bought mix or premade cookies to decorate instead.
Let the white icing dry fully before using black writing gel to draw the light strands.
Once you’ve added the gel, place the M&Ms on immediately, and push into the gel so they stick.