Preheat the oven to 200C.
Place flour and butter into a bowl and use your fingertips to mix in butter until it resembles fine breadcrumbs.
Add the cheddar and buttermilk, season with salt and pepper and mix until just combined.
Transfer to a floured surface and bring together. Roll out to 2 cm round and score into squares.
Transfer to a lightly floured baking tray. Brush with extra buttermilk and sprinkle with extra cheddar.
Bake for 20-25 minutes or until golden and cooked through. Set aside.
Heat butter in a large saucepan.
Add garlic and cook for 1-2 minutes or until lightly browned.
Add the flour and stir for 1 minute.
Add potatoes and stock, bring to the boil stirring occasionally.
Reduce heat and simmer for 10-12 minutes or until potatoes are cooked. Blend until smooth using a stick blender.
Peel and devein the prawns, removing the tails.
Return to saucepan and add the cream, corn and prawns and cook for a further 5 minutes or until the prawns are cooked.
Season with salt and pepper. Top with crème fraîche, crispy chopped pancetta and baby chervil to serve.