Make the crumble topping first. Put the plain flour, light brown soft sugar and cinnamon into a bowl and stir them together. Add the butter in chunks or cubes and rub it into the flour mixture with your fingers until it resembles breadcrumbs. You can also do this with a fork, a pastry blender or a food processor. Set it aside
Pre-heat your oven to 180C Fan/400F/Gas Mark 6, and line a cupcake tin with cupcake cases or muffin liners
In a large mixing bowl, add the plain flour, light brown soft sugar, caster sugar, baking powder, cinnamon and salt. Stir or whisk together
In another mixing bowl, or a jug, whisk together the eggs, milk, natural yoghurt and vanilla extract. Add the melted butter and mix it in
Pour the egg mixture into the flour mixture and whisk gently or stir to combine
Add the apple and mix it in
Divide the mixture between the cases. The cases should be filled to the top
Sprinkle the crumble topping over the muffin batter
Bake for 25 minutes, or until risen, golden and skewer inserted in the centre comes out clean. Put them on a rack to cool completely
Store leftovers in an airtight container in a cool place and eat within 3 days
Notes
I used melted butter for the recipe, which I do recommend for best results and flavour. However you can use a baking spread like Stork too.
Make sure your eggs are at room temperature before you start baking.
I used a mix of milk and yoghurt in the muffins, you can also replace this with buttermilk.
You don't have to sprinkle the muffins with the crumble topping, but I do recommend it for a crunchy top.
The muffins can be baked in cupcake cases or muffin cases/wraps.
Although I provide cup measurements, I highly recommend weighing your ingredients out using digital kitchen scales. It is the most accurate way to measure ingredients and will ensure the best results. Digital scales are very low cost and can be purchased for around £12 ($16.50).
For teaspoon (tsp) and tablespoon (tbsp) measurements, please use measuring spoons and not the type of spoons you eat with. Again this will ensure accuracy and provide the best results.