A creamy, cheesy savoury dish packed with green vegetables, covered in a lighter white sauce, and topped with a wholegrain crumble. Nutrient dense, rich, filling and balanced. Full of green vegetables you don't even notice yourself eating!
Preheat oven to 190C/375F/gas 5. Steam the frozen vegetables in a steamer or microwave according to packet instructions. I like to do the different veg individually in the microwave which takes about 10-15 mins (broccoli takes the longest) or in a steamer I start with the broccoli and then chuck in the spinach and peas for the last few mins of cooking time and it takes less than 10 mins. Drain the vegetables and squeeze any excess water out of the spinach. Pour the cooked vegetables and grated courgette into a large roasting or casserole dish and set aside.
Next, make the white sauce: Melt the butter in a large saucepan over medium heat until frothing and just starting to smell nutty and turn a light golden colour. Whisk in the flour and allow to cook for a minute, then slowly drizzle in the milk, little by little, whisking constantly and making sure the milk is completely combined and mixture smooth before adding more in. Whisk in the stock, mustard, nutmeg or allspice and salt & pepper. Bring to the boil and allow to simmer for a few mins, whisking constantly. You should have a fairly thick white sauce. Take off the heat and stir through the grated cheese, then pour the sauce into the dish with the green vegetables and mix well.
Finally, make the crumble: pour the flour, oats and salt into a food processor and pulse for 30 secs or so to break down the oats a bit and combine everything. Add in the cubed butter and pulse for another 30 secs or so until you combined with the flour but still leaving little chunks. Grab handfuls of the crumble mixture and squeeze, to help the butter form clumps, before topping the creamy vegetable mixture with it. Once the vegetables are completely covered with an even layer of crumble, scatter over some chopped nuts and seeds, and a little extra grated cheese, if using. Pop in the preheated oven for 25-30 mins, until the crumble topping is golden and cooked and the cheesy filling is bubbling up around the crumble. Serve on its own or with a green salad or fresh chopped tomatoes drizzled with extra virgin olive oil and a pinch of salt.