Preheat the oven to 300 degrees F (150 degrees C). Line two 12-cup muffin tins with paper liners.
Stir honey, coconut oil, eggs, and mashed bananas together in a large bowl.
Mix together spelt flour, baking soda, cinnamon, salt, and stevia powder in separate bowl. Gradually add flour mixture to honey-banana mixture, stirring until combined. Gently fold in blueberries. Scoop batter into the prepared muffin cups.
Bake in the preheated oven until tops spring back when lightly pressed, about 22 minutes. Cool in the tins for 5 minutes. Transfer to a wire rack to cool completely.