In a medium bowl, whisk flour, cardamom, cinnamon & salt. Set aside.
Mix the softened butter & brown sugar in a stand mixer with the paddle attachment until fluffy. Scrape down the sides of the bowl as needed. Then add the egg & the vanilla extract until fully combined.
On low speed, gradually add the dry ingredients to the wet ingredients until combined. Now, mix 1 1/2 Tbsp of orange zest & the orange juice into the dough.
Turn the dough out onto a floured work surface & divide into two. Shape divided dough into logs (about 2 1/2-inches in diameter), wrap in plastic wrap, and chill for at least 2 hours or overnight (recommended).
Preheat oven to 350 F. Line two baking sheets with parchment paper. Set aside.
Remove cookie dough logs from the refrigerator & slice each log into 12 equal sized cookies. Place cookies, about 2 inches apart, on lined baking sheets & bake for 12-14 minutes.
Allow cookies to cool for 5 minutes on the cookie sheets, then transfer to a wire cooling rack to cool completely.
Once the cookies are cooled, melt the chopped chocolate in a microwave-safe bowl in 15-second increments (stir after each increment) until completely melted & smooth.
Drizzle the chocolate over the cookies & sprinkle with sea salt & the remaining ½ tablespoon orange zest. Let chocolate set before serving.