1. To make the cookies: In a bowl, whisk together flour, cocoa, and salt. With a mixer, cream margarine and sugar until fluffy.
2. Add egg and mix well. Slowly add flour mixture and mix until well incorporated.
3. Divide dough into two pieces. Form two cylinders, about one and 1/2 – two inches (four to five centimeters) in diameter. Wrap well with plastic wrap and freeze for one hour.
4. Meanwhile, prepare the brittle: Line a baking sheet with Gefen Parchment Paper and spray with Glicks Cooking Spray. Place sugar in a pan (preferably nonstick) and melt over medium heat until it becomes completely liquid. Watch carefully and remove from heat as soon as it’s melted. Whisk in margarine to melt quickly and stir in peanuts. Pour onto prepared baking sheet and spread out thinly. When brittle is fully cooled and hardened, break into small pieces and crush.
5. Once cookie dough is ready, preheat oven to 350 degrees Fahrenheit (175 degrees Celsius).
6. Slice cookie dough into 1/4-inch (0.6-centimeter) slices. Place on a lined baking sheet and bake for nine minutes. Allow to cool.
7. Mix all frosting ingredients with a whisk until smooth. Dip each cookie halfway into frosting. Top with crushed peanut brittle.
Although this recipe has many steps, each component can be made separately in advance and frozen. You can save the step of making your own brittle and just used some crushed honey-roasted peanuts instead.
If you or anyone you’re serving has nut allergies, the frosting can be made with caramel cream or Lotus butter, and the peanut brittle replaced with crushed Lotus cookies or something similar.