Preheat the oven to 180C.

Make the butter by beating the butter, tarragon and vinegar in a food processor. Taste and add more vinegar if necessary. Spoon into a small bowl and set aside at room temperature.

Line a 2lb loaf tin with baking parchment.

Bring a pan of water to the boil. Gently bend each asparagus spear until it snaps. It will break at just the right point. Simmer the asparagus in the water for 3 minutes until just done. Rinse in cold water and set aside.

Heat a small frying pan and add the pancetta. No need for any additional oil. Fry the meat till it is crisp and cooked through. Set aside.

Whisk the oil, milk and eggs in a jug. Sieve the flour and baking powder into a wide bowl. Create a well in the centre. Add the black pepper and pour in the wet mix. Fold together gently until just mixed. Place a few spoonful of the batter into the base of the tin. Lay about 6 asparagus spears down in the batter. Top with some more batter and then scatter with some pancetta. Repeat one more time with the remaining batter, asparagus and pancetta, finishing with a layer of batter. Place one or two asparagus spears on top. Bake for 40-45 minutes until lightly golden. Test with a skewer to ensure the inside is cooked. Cool on a wire rack. Serve warm with the butter and a green salad.