In a large mixing bowl, using an electric hand mixer, blend the butter until smooth, then add the egg and fully incorporate. Slowly add the dry cookie mix and blend until a dough forms. Gather the dough into flat disc and wrap in plastic. Chill 20 minutes or until firm.
Remove dough from refrigerator and preheat oven to 350 degrees. Line two baking sheets with parchment paper, set aside. Generously flour a flat surface and each side of the dough, then using a rolling pin, roll dough out until about 1/4 inch thick. Using a heart cookie cutter, cut out cookies and place on prepared pans, about 1 inch apart. Repeat with remaining dough. Freeze cookies 5 minutes, then remove from freezer and bake for 15 minutes, or until the edges of the cookies begin to turn golden. Cool completely on a wire rack.
To make the glaze, in a large bowl, combine the glaze mix and the milk. Whisk until smooth and pourable. Divide glaze evenly into 6 small bowls, or as many colors as you desire to make. Place a few drops of red dye into one of the bowls, this glaze will be used for the words on each cookie.
Dye each remaining bowl of glaze in desired colors, stirring each well. Use a small spoon or popsicle stick and spread about 1 teaspoon of desired colored glaze onto each cookie. Place cookies on a sheet pan and freeze five minutes to set the glaze. Pour red glaze into a piping bag or plastic storage bag, secure the top and place in the freezer for 5-7 minutes.
Once the glaze has set on the cookies, remove cookies and red glaze from freezer. Snip the tip from the end of the piping bag, and pipe desired phrase onto each heart cookie. Place back in freezer at least 5 minutes to set writing.