Using your Russell Hobbs kettle, brew the earl grey tea and let it sit and cool until you are ready to mix the cake.
Grease and line a 23cm spring-form cake tin and pre-heat your oven to 180°c.
In a food processor, blitz the crumble ingredients into a fine crumb and set aside.
Using electric beaters or a stand mixer, cream the butter and sugar until pale and fluffy. Add the eggs one at a time, followed by the tea and mix to combine. Stir in the flour alternately with the yoghurt, stirring well after each addition.
Pour the cake batter into the prepared cake tin and sprinkle the crumble mixture over the top. Bake in the pre-heated oven for 45-50 minutes until golden brown on top and cooked in the middle (insert a skewer into the centre of the cake and if it comes out clean, it’s ready). Leave the cake to cool in the tin for at least 10 minutes before serving.