Photograph: Dan Jones
Preheat the oven to 200°C, fan 180°C, gas 6. First make the topping. In a bowl, rub together the butter and plain flour until you have a crumbly consistency. Add the grated cheddar and a pinch each of salt and pepper. Mix until combined, then set aside while you make the muffin batter.
Line a 12-hole muffin tin with muffin cases. Sift the flour, bicarbonate of soda and baking powder into a large bowl. Add a pinch of salt. Break the blue cheese into bite-sized pieces and scatter into the bowl, along with the chopped pear and walnut pieces. Stir to combine. In a jug, whisk together the yogurt, eggs and milk. Pour the mixture in the jug into the dry ingredients and fold in with a large metal spoon until just combined – but don't overwork it.
Spoon the batter into the prepared muffin cases and sprinkle over the topping. Bake in the preheated oven for 25-30 minutes or until well risen and golden brown. Transfer to a wire rack to cool completely before serving.
Kitchen secret: for light, airy muffins, be careful not to overmix the batter. Cool muffins on a wire rack, out of the tin, to stop the bottoms becoming soggy.