Chop butter up into small pieces and add all the other ingredients.
Work with your hands until the butter is incorporated into the dry ingredients .
Set aside.
FOR THE CAKE
Preheat the oven to 160ÂșC.
Grease a loaf pan and line with baking paper. I use one long strip along the bottom and up the two short sides, so that it is easy to lift the cake out once cooked.
Put eggs, oil, yoghurt, salt lemon juice and caster sugar in a large bowl and whisk until well combined.
Whisk the sifted self raising flour into the wet ingredients in batches of three until the mixture is smooth and has no lumps in it.
Pour the mixture into your prepared loaf pan ( or a 24cm spring form circular pan)
Sprinkle the blueberries over the top and press down into the mixture.
Add the nut topping and back for 1 hr 20 minutes or until a skewer comes out clean from the cake.
Recipe by Shades of Cinnamon at https://www.shadesofcinnamon.com/blueberry-and-pecan-crumble-cake/