Preheat oven to 350 degrees F (175 degrees C). Butter a 10x15-inch baking dish or line a deep baking sheet with parchment paper.
Mix buckwheat flour, cinnamon, baking soda, salt, and nutmeg together in a bowl. Beat honey, peanut butter, olive oil, eggs, and vanilla extract together in a separate bowl; mix into flour mixture. Fold oats and chocolate chips into flour mixture; spread into the prepared dish.
Bake in the preheated oven until edges are lightly browned, 15 to 20 minutes. Cool completely on a wire rack before cutting into bars.