Heat your oven to 200°C/Fan 180°C/Gas 6. Halve the butternut squash lengthways. Scoop out the seeds. Slice a criss-cross pattern into the cut sides of the squash. Pop in an ovenproof dish. Drizzle each half with 1 tsp oil. Cover with foil. Roast for 35 mins till tender.
While the squash roasts, tip the flaked almonds into a dry frying pan. Toast over a lowish heat for 3-4 mins till the almonds are golden brown. Shake the pan while they toast. Tip into a bowl. Set aside.
Trim the very top and bottom off the leek. Halve it and rinse out any grit. Slice it. Put the frying pan back on the heat. Add 2 tsp oil and the leek. Season with salt and pepper. Gently fry for 8-10 mins over a low heat till soft. Stir now and then. Strip the leaves off half the thyme sprigs.
Slide a skewer or a tip of a knife into the squash halves to check that they’re soft. Scoop the flesh out of them into a bowl, leave a ½ cm thick rim of squash in the skins. Mash the squash flesh till smooth. Stir in the leek, half the toasted almonds and the thyme leaves.
Crumble the Stilton and stir half into the squash mash. Taste and season. Spoon the mixture back into the skins. Top with the remaining Stilton. Return to the oven for 15 mins till golden and bubbling.
While the squash finishes cooking, whisk 1 tbsp vinegar with 2 tsp oil and some salt and pepper in a bowl to make a dressing. Toss the peppery salad leaves with the dressing.
When the squash is golden, take it out of the oven and serve with the salad. Scatter over the last of the toasted almonds and a few more thyme leaves to garnish.