Place a rack in the center of the oven and preheat to 350° degrees. Line a 12-cup muffin tin with liners.
Melt the butter in a heavy saucepan over medium heat. Butter will begin to foam and crackle as it melts. When the crackling subsides, the butter will begin to brown. Swirl the pan as the butter cooks. When the butter browns and begins to smell nutty, remove the pan from the flame and transfer the butter to a small bowl. Taking the butter out of the hot saucepan will stop the butter from overcooking and burning. Set it aside to cool.
In a large bowl, whisk together the oat flour flours, sugar, baking powder, baking soda, salt, cinnamon, and cardamom.
In a medium bowl, whisk together eggs, yogurt, and vanilla extract. Whisk in the mashed bananas and molasses. When butter has cooled, whisk in the browned butter.
Add the wet ingredients all at once to the dry ingredients. Fold together, making sure to scrape the bottom of the bowl to reveal any hidden pockets of flour. Fold in the chocolate chips.
Pour batter into prepared pan. Bake for 25-30 minutes, or until a skewer inserted into the center of a muffin comes out clean. Remove from the oven and allow to rest in the pan for 15 minutes, before inverting onto a wire rack to cool completely.
Muffins may be stored in an air tight container in the fridge for 5 days.