fancy chocolate cookie time

I've been working on a cookie recipe for a contest and this is where I'm at right now. The cookie is similar to a macaroon studded with toasted walnuts and the filling is a dense chocolate ganache made with coconut milk and chocolate. A friend named them the mayan a-choco-lypse! ;)

For The Cookies 

4 cups powdered sugar

1/2 cup unsweetened cocoa powder

1/2 teaspoon salt

1/2 teaspoon cardamom

3 cups toasted walnuts toasted and chopped (bake 320 for 10-15 min)

4 large egg whites (room temperature)

1 tbl vanilla 

For Frosting 

1/8 teaspoon cardamom 

pinch of sea salt

1/2 cup unsweetened coconut milk (before opening shake can to combine cream at the top)

1/2 cup of milk chocolate chips (or a 3 ounce chocolate bar)

1/2 cup unsweetened cocoa powder

Directions
1.  Preheat oven to 320 degrees, with racks in upper and lower thirds. Line two baking sheets with parchment paper; set aside. In a medium bowl, whisk together flour, cocoa powder, baking soda, salt, pepper, cinnamon, and cardamom. 

2.  Add in walnuts, egg whites, vanilla and stir until just combined. Drop by level tablespoons onto parchment-lined baking sheets about two inches apart. 

3.  Bake until tops are glossy brown, rotating sheets halfway through, 12 to 15 minutes. Leave cookies on parchment and slide them onto a wire rack to cool.  

4.   Make frosting: Place cardamom, pinch of salt, unsweetened coconut milk, and 6 ounces of chopped milk chocolate in a small saucepan over low heat, stirring until melted and smooth. Gradually mix in cocoa powder with a whisk until fully incorporated. Allow mixture to stand for 10 minutes to cool. Spread frosting on flat sides of half the cookies and top with remaining cookies. Approximately 1 heaped tablespoon of frosting per cookie sandwich.