4. Pour the sweetened condensed milk over the crumbs and work into a dough with a spatula. If making the chocolate version, add the cocoa powder to the sweetened condensed milk and stir to combine well before pouring over the crumbs. Gently knead the cookie dough into a ball
5. Place the dough between two sheets of parchment paper. With a rolling pin, roll the dough to an even ¼ inch or about 0.6 cm thick. Using a 1 ½ inch or 3.5 cm cookie cutter, cut out all your cookies. Place the cookie cut-outs onto a parchment-lined baking sheet
7. Place the cookie sheet into the middle position of a 320 F or 160 C preheated oven. Bake for exactly 10 minutes. Remove the tray and let the cookies cool for 15 minutes before transferring onto a cooling rack
8. Flip the solid cookies so the top of the cookie is placed down on the cooling rack. Match and line each solid cookie with the donut shaped cookie. Place the chilled Sugar Free Sweetened Condensed Milk, or the Dairy Free Sweetened Condensed Coconut Milk into a piping bag. Squeeze out, to the center of the solid cookie, the condensed milk, so that it covers about half of the solid cookie. Place the donut shaped cookie over the condensed milk and press down lightly so the condensed milk fills the center hole. Repeat until all the cookies have been filled and assembled
9. Place the tray of assembled cookies into the refrigerator for about 15 – 20 minutes before serving. Store in an airtight container lined with paper towel and place in your refrigerator. The cookies will keep for 5 days. Enjoy!