Lemon-Sugar Blueberry Muffins

Heat and prepare. Set a shelf in the middle of the oven and heat it to 220 °C (200 °C fan). Line or grease the 12-hole tin. A hot start pushes the batter up quickly into tall domes.

Make lemon sugar. Rub the lemon zest into the 60 g granulated sugar with your fingertips until it smells strongly of lemon. Rubbing releases the oils from the zest so the topping is fragrant as well as crunchy.

Cook some berries. Put 100 g of the blueberries in the small saucepan over medium heat and simmer for 4-6 min, mashing as they burst. Once they look jammy and have reduced to about 4 tbsp, take them off the heat and let them cool. Concentrated berries give a deep fruit flavour without making the batter wet.

Whisk the dry mix. In a large bowl, whisk together the flour, baking powder and salt. An even mix means every muffin rises the same way.

Whisk the wet mix. Beat the 210 g caster sugar with the eggs in the second bowl for about 45 seconds, until thickened. Whisk in the melted butter and oil, then the buttermilk and vanilla. Butter brings flavour while the oil keeps the crumb moist for longer.

Fold together. Tip the wet mix into the flour and fold with a spatula until only a few dry streaks remain. Add the remaining 200 g fresh blueberries and fold just until no flour is visible. Over-mixing develops gluten and makes muffins tough and tunnelled.

Fill and swirl. Divide the batter between the 12 holes; it will come right up to the rim. Spoon 1 tsp of cooked berries onto each and draw a cocktail stick through in a figure of eight, then scatter the lemon sugar evenly over the tops.

Bake until springy. Bake for 17-19 min, turning the tin round halfway. They are done when golden, springy when pressed lightly and a cocktail stick pushed into the centre comes out clean, at about 96 °C inside.

Cool briefly. Leave them in the tin for 5 min so the crumb firms, then lift them onto the rack for another 5 min before serving. Cutting in too soon squashes the soft centre.