Preheat the oven to 200C/180C Fan/Gas 6. Line a 6 hole muffin tin.
In a large bowl, combine the flour, baking powder and sugar.
Make a well, and pour in the milk, egg, oil and butter (make sure it has cooled a little first). Add the zest and juice from the orange and stir gently with a wooden spoon until just combined.
Scoop 1 tbsp batter evenly into each muffin hole.
Use a teaspoon to scoop 1 tsp marmalade in the centre of each muffin. Top off with enough batter to cover the preserve without overfilling the muffin cases (never go too far above 2/3rds full).
Bake for 18-20 minutes, until golden on top. Gently brush over more marmalade for extra sticky goodness, and top with a little more zest if desired. Remove from the tin and let cool on a wire rack – highly recommend eating whilst still warm!