Pre-heat the oven to 180ºC/350ºF and put 12 paper cases into the muffin tin.
Make the crumble topping: Put all the ingredients into a food processor and pulse until the butter has dispersed evenly and it looks like large breadcrumbs. Alternatively, you can rub the butter into the flour with your fingertips and then stir in the oats and sugar.
For the muffin mixture: In a large bowl, using an electric whisk, beat the butter until creamy. Add the sugar and beat again until pale and fluffy.
Add the eggs, one at a time, beating well. Add the lemon zest, lemon extract and the baking powder and beat again.
Using a large spoon or spatula, gently fold in half of the flour, followed by half of the milk into the batter. Fold in the rest of the flour and then the remaining milk, followed by the blueberries.
Spoon the mixture into the muffin cases, so they are about ¾ full, and top with a teaspoon of the crumble topping.
Bake for about 25-30 minutes, until golden brown and firm to the touch.
Makes approximately 11-12 muffins, depending on the size of your muffin tin. The crumble topping is optional and it makes more than you need, but the extra topping freezes really well, as do the cooked muffins.
Tip: Take a spoonful of the flour and sprinkle over the blueberries to coat them. This should help to stop them sinking to the bottom of the cupcakes when cooked.
Please note: this recipe has been created and uploaded by a member of the Tesco Real Food online community. Tesco does not test customer recipes so cannot accept responsibility for the content, validate the results or answer queries regarding them.