In a large bowl, mix ½ cup melted butter, ½ cup granulated sugar, and ⅓ cup packed brown sugar until combined.
Add 1 large egg and 2 tsp vanilla extract to the butter mixture and mix until well combined.
Add 1½ cups light buckwheat flour, ½ tsp baking soda, ¼ tsp baking powder, and ½ tsp salt, and mix until just combined.
Fold in ¾ cup semi-sweet chocolate chips until evenly distributed. Cover bowl with plastic wrap and refrigerate dough for 60 minutes.
Preheat oven to 350°F. Line baking sheets with parchment paper.
Scoop dough into 12 portions and roll into balls. Place on prepared baking sheets 2 inches apart.
Bake for 10–12 minutes, until edges are set, but centers still look slightly underdone. Cool on a baking sheet for 5 minutes, then transfer to a wire rack to cool completely.