Cut the pumpkin into 3 cm wedges and scrape away the seeds. Cut the skin off if you wish, but I prefer to leave it on.
Cut the bullhorn pepper into 1½ cm rings, discard the seeds. Separate the cloves from the bulb of garlic, leaving the skin on.
Put the pumpkin, bullhorn pepper, walnuts and garlic cloves into a mixing bowl. Snip or tear the rosemary into it and then mix it all together with the oil, salt and pepper.
Don’t add the cheese yet.
Arrange it all in a single layer on a roasting tray, put it into the preheated oven and bake for 40-50 minutes.
Now make the dressing.
Combine all the dressing ingredients in a bowl and whisk to combine. Alternatively put them into a screw-top jar and shake to emulsify.
When the pumpkin is done baking, simply arrange it on a serving platter or board with the bullhorn pepper. Take each clove of garlic and gently squeeze it to extract the insides, then dot them around the pumpkin and peppers.
Give the dressing a bit of a stir, drizzle it over the vegetables, then shave the manchego over everything.