Preheat the oven to 175°C. Grease a 20cm springform tin and line with baking paper.
To make the streusel, combine the flour, sugars, cinnamon and salt. Rub in the butter until coarse crumbs form, then stir through the chopped nuts. Refrigerate while you make the cake.
Cream the butter and sugar until pale and fluffy. Beat in the eggs one at a time, followed by the vanilla. Add the yoghurt and milk and mix well. In a separate bowl, whisk together the flour, baking powder, salt and cinnamon.
Add the dry ingredients folding with a spatula, mixing until just combined.
Spread half the batter into the prepared tin and scatter over one-third of the streusel. Top with the remaining batter, then scatter over the remaining streusel.
Bake for 50-60 minutes, or until a skewer inserted into the centre comes out clean or with a few moist crumbs. Cover loosely with foil if the top browns too quickly.
Cool in the tin for 15 minutes before transferring to a wire rack. Serve slightly warm or at room temperature, with more Vanilla Bean Greek Yoghurt.
