Preheat the oven to 190°C, fan oven 170°C, gas mark 5. Put 8 paper muffin cases into a muffin pan, or line them with squares of nonstick baking paper.
Sift the flour, salt and baking powder into a large mixing bowl. Stir in the crumbled Stilton. In a jug, beat together the egg, milk and oil.
Pour the liquid mixture into the dry ingredients. Stir until just combined, adding the grated carrots and watercress at the last moment. You mustn’t beat the mixture or stir it too much. It should be quite lumpy, but there should be no traces of dry flour.
Spoon the mixture into the muffin cases. Bake for 20-25 minutes until risen and golden. Cool until the muffins are barely warm.
Cook’s tip: Why not make a batch of these yummy muffins for a relaxed breakfast or Sunday brunch? For mini versions, you’ll need to bake them in mini paper muffin cases in a mini muffin pan.