Step 1

Preheat oven to 350°. Line baking sheets with parchment paper or grease the sheets well.

Step 2

Using an electric mixer, cream the margarine and brown sugar until light and fluffy. Beat in vanilla.

Step 3

In a separate bowl, stir the salt into the flour. Add the flour to the creamed mixture alternately with the milk. Mix until just incorporated. Gently mix in the chopped chocolate. Don't overmix the dough. If you can, chill the dough for an hour or more.

Step 4

Roll dough into 1" balls and place on the cookie sheets at least 2" apart. (If the dough is a little crumbly when rolling, just roll in your hand a little bit longer.) Make a deep depression in each dough ball with either your thumb or with a wine cork. Don't break through the bottom of the dough. If the cookie cracks a little once depressed, just smooth the edges back together.

Step 5

Bake 10-12 minutes until the bottoms of the cookies are a little golden. Let cool on the sheet pan a few minutes, then pick up the whole parchment sheet and transfer to a rack or countertop. If not using parchment, just transfer the cookies to a rack or even to newspaper on the countertop. Cool completely.

Step 6

In a double boiler bottom, heat 1" of water to barely simmering. In the top half of the boiler, place chocolate chips, shortening, corn syrup, vanilla and water. Heat gently, stirring frequently, until completely melted and smooth. (You can also do this in the microwave, but be very careful to heat GENTLY.)

Step 7

Push your cookies together on the parchment - it makes filling easier. Place your whole double boiler on a hot pad beside the cookies. Using a soup spoon or another deep spoon, carefully fill the cookies. One scoop of the spoon will usually fill more than one cookie. You'll get the hang of it.

Step 8

Allow the cookies to cool for at least an hour to set the filling.