Put the pumpkin or squash in a large heatproof bowl, add 1 tbsp water, cover with cling film and microwave on High for 5-8 mins or until really soft – different types will take a varying amount of time. Drain the pumpkin well and cool completely. If you want to eat the pancakes for breakfast, this step is best done the night before.
Once cool, put the pumpkin in a food processer with the remaining pancake ingredients and add a good pinch of salt. Blend until everything is well combined to a smooth, thick batter (alternatively, mash the pumpkin well, then whisk in the remaining ingredients). Transfer to a jug or piping bag and set aside while you make the butterscotch sauce.
Toast the pecans in a saucepan for 1-2 mins until a shade darker. Tip out and set aside. Add the butter, sugar, salt and cream to the pan. Bring to a simmer, then bubble gently for a few mins until you have a shiny sauce. Stir in the pecans and set aside to cool a little.
Heat a knob of butter and a drizzle of oil in a large frying pan. Heat oven to 140C/120C fan/gas 1, to keep the pancakes warm while you cook them in batches – have a baking tray to hand. When the butter is foaming, swirl it around the pan, then pour tennis-ball-sized amounts of batter into the pan (see tip below) – they will spread a little as they cook, so leave some space between each pancake and don’t overcrowd the pan. Cook over a low-medium heat. Don’t touch the pancakes until you see a few bubbles appear on the surface – have a look underneath and, if the pancakes are golden, flip them over and cook for another 2 mins on the other side. Transfer the cooked pancakes to the baking tray and keep warm in the oven while you continue cooking.
Once cooked, pile the pancakes onto plates, top with ice cream, yogurt or crème fraîche, and pour over the salted pecan butterscotch sauce.