Bring a large pan of lightly salted water to the boil and cook the penne as per the packet instructions, then drain. Meanwhile, heat a large frying pan over a medium heat, add the butter and fry the leek and kale for 10 minutes or until the leaves are tender but still dark green and slightly firm.
Stir in the cream cheese, smoked mackerel and horseradish sauce and heat for 1 minute.
Stir in the pasta and season with black pepper.
Pour everything into an oven proof baking dish, scatter with breadcrumbs and cheese and grill until the top is crisp and golden.
Simmer the broccoli in a pan of boiling water for 4 - 5 minutes until tender. Serve the pasta bake together with the broccoli
Smoked mackerel fillets are already cooked, which makes them a very easy ingredient for a pasta bake. You can buy the fillets simply smoked or with added flavours such as smoked peppered mackerel, hot smoked, or even honey and soy flavoured.
I've used leeks and kale in this recipe, but you could also use onion in place of the leeks and green cabbage or spinach to replace the kale. Fresh spinach doesn't need cooking, just stir it into the pasta at stage 3 so it wilts down.
You can use any pasta shapes in a pasta bake.
For the topping, use a hard grated cheese such as cheddar or mozarella. Mozarella has a milder flavour. I also take the opportunity to sprinkle over some breadcrumbs for a more crunchy topping. Breadcrumbs are a great way to use up any leftover bread that is past its best. Remember that you can store breadcrumbs in the freezer and use them from frozen so this can help minimise your food waste.
Smoked mackerel fillets can be frozen for up to 3 months. They also keep well in the fridge for up to several weeks. Store the pasta bake in the fridge for 2-3 days in an airtight container to prevent the smell of the fish leaking into the other food.You can prepare this smoked mackerel pasta bake ahead of time and keep in the fridge. To re-heat, cover with foil and re-heat for 20 minutes at 180°C/350°F. Remove the foil and bake for another 10-15 minutes.