Sift the flour, baking powder and salt together. Set aside.
In a large bowl, cream the butter and sugar until light and fluffy. Add the milk. Add the eggs one at a time, beating well after each addition. Beat in the lemon, almond and vanilla extracts.
Beat in the dry ingredients gradually, and beat well to mix; the dough will be soft. Wrap it in waxed paper and refrigerate it for 1 hour to make it easier to handle.
Preheat the oven to 350 degrees F. Lightly grease 2 cookie sheets.
Place the dough on a well-floured surface. Pinch off small egg-size pieces of dough and roll each piece into a rope about 7 inches long and the width of your middle finger. Tie into a loose knot and place 1 inch apart on the prepared cookie sheets.
Bake for 12-15 minutes, or until lightly browned.
Transfer the cookies to wire racks to cool slightly.
For the frosting, in a bowl, combine the sugar and 1/4 cup of the milk and beat until smooth. Add more milk if necessary to make a thin frosting. Beat in the almond extract. Add food coloring, if desired.
Dip the top of each cookie into the frosting, shaking off the excess. Place them on racks and sprinkle with colored sprinkles, if desired.
Let the frosting dry before storing. These will keep in an airtight container for up to a week; or freeze them for up to 3 months. If freezing, do not frost until ready to serve.