For the honey and thyme butter, use the back of a wooden spoon to crush the thyme leaves and release their aroma, then finely chop them. In a medium-sized bowl, use a wooden spoon to beat the butter until light and fluffy. Add the thymeleaves, honey and salt, and mix to combine. Tip onto a piece of parchment paper and form the butter into a log or rectangle. Wrap the parchment paper around the butter and refrigerate. Remove from the refrigerator 10 minutes before ready to serve to allow it to soften slightly.
Preheat the oven to 180°C/160°C fan. Brush a 12-cup muffin tin with 1 tsp of the melted butter.
For the muffins, sift the plain flour and baking powder into a large bowl, then stir in the caster sugar, salt and nutmeg. Make a well in the centre, then add the milk, eggs, vanilla bean paste and the remaining melted butter, and mix until combined.
Divide the batter evenly among the muffin cups - they should be quite full. Bake for 25 minutes, or until the tops are golden and a skewer inserted in the middle of a muffin comes out clean. Let cool for five minutes.
For the topping, in a small bowl, mix together the caster sugar and cinnamon. Pour the melted butter into a separate small bowl.
Remove the muffins from the tin and dip the tops into the melted butter one at a time. Shake off any excess, then immediately roll the muffin tops in the cinnamon sugar.
Serve the muffins warm with the honey and thyme butter on the side.