Preheat oven to 400°F. Prepare muffin pan (with twelve 2½-inch diameter cups) by generously buttering the cups or lining cups with paper liners.
Whisk together flour, baking powder, baking soda, salt and brown sugar in a bowl, create a well in the center of the mixture, and then set this mixture aside.
Melt butter and allow it to cool slightly. Whisk together buttermilk, egg, and melted butter.
Add wet ingredients all at once to well in dry ingredients. Stir just until dry ingredients are moistened; do not over mix. Fold in nuts and raisins.
Spoon batter into 12 prepared muffin cups. Bake 20 minutes or until tops are browned and a wooden toothpick inserted in a muffin comes out clean. Serve muffins warm with honey butter.
Beat ½ cup (1 stick) room temperature (or slightly softened) Challenge Butter with ¼ cup honey until smooth.
Note: *Grind oatmeal in a blender or food processor for a few seconds to obtain coarse flour.