Preheat oven to 375F and line a baking sheet with parchment paper.
In a small sauce pan, stir together the cranberries, sugar, cardamom, orange juice and zest and bring to a low boil, stirring occasionally to ensure the mixture doesn't burn. Once the mixture starts to thicken, remove from heat and stir in the chia seeds. Cover and let cool.
To make the cookie dough, add 1/4 cup cane sugar, cashew butter and coconut oil to a large mixing bowl and use an electric mixer to beat together until creamy. Beat in the egg and vanilla.
In a small bowl, sift together the buckwheat flour, almond flour, baking soda, baking powder and salt. On low-speed, gradually add the dry ingredients to the wet mixture until a dough forms. You may need to stop a few times to scrape down the sides of the mixing bowl.
Add the remaining 1/4 cup cane sugar to a small plate. Shape the dough into roughly one-inch balls and roll in the sugar. (You should get 12-14 balls). Arrange about 2-inches apart on the baking sheet and use your thumb to create a well in the centre of each cookie.
Bake for 8 minutes and remove from oven. If the thumb impressions have disappeared, carefully use a 1/4 teaspoon to reshape them. Add the cranberry filling to each thumb impression. Return to oven and bake for another 5 minutes. Let cool on the pan for a few minutes before transferring to a wire rack to cool completely.
For the optional chocolate drizzle, add the dark chocolate chips and coconut oil to a small microwave safe bowl and microwave in two 30-second intervals, stirring in between and after until smooth. Drizzle the chocolate over the cookies.
Store cookies in an airtight container in the refrigerator or freeze for up to 3 months.