Pre-heat the oven to 200°C and grease a six-hole muffin tray (or line with cases).
Beat butter, sugars and oil together. Beat in the egg. Then add the baking powder, baking soda, vanilla, nutmeg and cinnamon and stir until just combined.
Stir in half of the flour, then half of the milk. Repeat. I used my KitchenAid on the lowest setting just until everything came together.
Fill the muffin cases (or tin) half way up with batter. Dollop one teaspoon of jam on top. Cover with remaining batter. Bake for around 17 minutes.
Allow the muffins to cool a little. Then, melt the butter and brush over the still warm muffins. Mix the cinnamon and sugar and dip the muffins in and roll them about a bit until there is an even coverage. Enjoy!