To make the streusel topping, mix together the flour, sugar, cinnamon and a pinch of salt in a bowl then rub in the butter using your fingertips until no lumps of butter remain and the mixture is clumping together. Place the bowl in the fridge while you make the muffin batter.
90 g (¾ cup) plain (all-purpose) flour, 70 g (packed ⅓ cup) light brown soft sugar, 1 teaspoon ground cinnamon, pinch salt, 60 g (¼ cup) vegan block butter
Whisk together the pumpkin puree, yogurt, oil, milk, sugar, vinegar and vanilla extract in a large bowl.
425 g (15 oz) pumpkin puree, 125 g (½ cup) vegan Greek style yogurt, 165 g (¾ cup) neutral oil (I use olive), 80 g (⅓ cup) unsweetened non-dairy milk (I use soy), 225 g (1 cup + 2 Tablespoons) light brown soft sugar, 2 teaspoons vinegar, 2 teaspoons vanilla extract
Whisk in the pumpkin spice, baking powder, bicarbonate of soda and salt, followed by the flour. Be careful not to over-beat the batter, just mix it until no streaks of flour remain.
4 teaspoons pumpkin spice*, 2 teaspoons baking powder, 1 ½ teaspoons bicarbonate of soda (baking soda), ½ teaspoon salt, 400 g (3 ⅓ cups) plain (all-purpose) flour
Cover the bowl with a tea towel and let it rest for 15 minutes. Meanwhile, preheat the oven to 220°C/200°C fan/425°F/gas mark 7. Line two muffin tins with 12 cases, spreading them out across the tins so that there is a gap in between each one.
Divide the batter between the muffin cases, filling them all the way to the top. An ice cream scoop is handy for this.
Scatter the streusel mixture generously over the top of each muffin. It may seem like a lot of streusel but the muffins will rise and spread a lot so use it all!
Bake the muffins for seven minutes then turn the oven down to 180°C/160°C fan/350°F/gas mark 4. Bake for a further 15-17 minutes, until a skewer inserted into the centre comes out clean.
Allow the muffins to cool in the tin for 5 minutes, then transfer them to a wire rack and leave to cool completely. Once cold store in an airtight container. Best eaten on the day they are baked.