Preheat your oven to 350 degrees F. Line a baking sheet with parchment paper or a Sil-Pat.
In a medium mixing bowl, combine the flour, cocoa powder, and cloves.
In a large mixing bowl, beat together the butter and brown sugar until fluffy. Add the lemon zest and mix to combine.
Add the flour mixture to the butter mixture and mix well.
If your dough is looking extremely dry, add 1 tablespoon of milk and mix to combine. Check the dough with your finger tips; it should squish together easily and not be crumbly. If it's still too dry, add 1 more tablespoon of milk and mix.
Stir in the nuts.
Divide the dough and roll into two long dough ropes, about 1-inch thick. Cut the dough rope into 2-inch long pieces. (I got 7-8 pieces per rope.) Cut each of these pieces in half (so there are two long pieces).
Place the cookies, flat (cut) side down on your prepared baking sheet, about 1 1/2-inches apart - the cookies will spread. Bake for 15 to 20 minutes, or until the cookies are set.
Remove from the oven and cool on the baking sheets for a complete minutes before transferring to a wire rack to cool completely.
Topping:
Line a baking sheet with waxed paper.
In a microwave safe bowl, heat together the chocolate chips and oil for 30 seconds. Remove the bowl and stir the chocolate. Repeat heating for 30 seconds and then stirring until the chocolate is melted and smooth. (DO NOT over heat or the chocolate will seize.)
Dip one end of a cooled cookie into the melted chocolate, let the excess chocolate drip off a little.
Place the cookies on the prepared baking sheet and sprinkle the chocolate with nonpareils, sprinkles, or nuts. Repeat with remaining cookies.
Let the chocolate cool until set. (I popped mine in the fridge to help speed the chocolate cooling time.)
Notes
For the Vanilla version: Change out the brown sugar for the same amount of granulated sugar, leave out the cocoa powder, increase the flour to 1 1/2 cups total, and add 1 teaspoon of vanilla. Prepare as directed.