For the peas, heat the butter in a small saucepan over a medium heat and gently fry the onion until softened but not coloured. Add the garlic and cook for one minute.
Add the peas and white wine. Bring to the boil and simmer until the wine has reduced by half.
Add the double cream and simmer until slightly thickened. Season with salt and freshly ground black pepper and set aside to keep warm.
For the trout, place the almonds, dill and butter into a bowl and mix well.
Heat the almond and dill butter in a frying pan and fry the trout for 2-3 minutes on each side, turning with a fish slice, until golden-brown and completely cooked through.
To serve, place the peas onto a plate, top with the trout and pour over the butter left in the pan. Garnish with a sprig of dill.