Preheat the oven to 200C/180C Fan/Gas 6.
Place the sprouts into a saucepan of simmering salted water and cook for 4-5 minutes, until almost, but not quite, cooked. Drain thoroughly, allow to cool slightly, then cut in half.
Place the butter and oil into a wide frying pan over a medium heat. Add the bacon lardons and almonds and gently fry for 3-4 minutes, until lightly browned.
Add the sprouts and fry for a further 2-3 minutes, stirring constantly.
Add the cream and bring the mixture to the boil. Boil for 2-4 minutes, until the cream has reduced to a rich sauce. Season to taste with salt and freshly ground black pepper.
Remove from the heat, add the lemon juice and spoon into an ovenproof gratin dish.
Mix the breadcrumbs and Parmesan together in a bowl, then sprinkle evenly over the top of the sprout mixture.
Place into the oven and bake for 20 minutes, until the top is golden-brown and the cream visibly boiling.
Remove from the oven and serve in the gratin dish (when the dish has cooled slightly).