Preheat the oven to 375°F (190°C). Grease or line a 12-cup muffin tin with paper liners.

In a medium mixing bowl, combine the wheat bran, oat bran, and milk. Stir and let stand for about 10 minutes so the bran can hydrate.

In a large mixing bowl, whisk together the oat flour, baking powder, and salt. Set aside.

In a small mixing bowl, beat together the egg, honey, molasses, light brown sugar, and softened butter until smooth and well combined.

Stir the soaked bran mixture into the wet ingredients, then add the raisins or currants if using.

Make a well in the dry ingredients and pour in the wet mixture. Gently fold together with a spoon or spatula until just combined. If the batter looks very thick, add 1–2 tablespoons of extra milk to loosen it.

Divide the batter evenly among the muffin cups, using about 1/2 cup of batter per muffin for large bakery-style muffins.

Bake for 25–30 minutes, checking from 20 minutes. The muffins are done when a toothpick inserted into the centre comes out clean.

Let the muffins cool for 5 minutes in the pan, then transfer to a cooling rack. Serve warm, as Murray’s always did, with butter.