Preheat oven to 180c degrees. And grease a 9inch round baking pan (but you can also use a 8x8 or 9x9 square baking pan. Set aside.
In a medium sized bowl, mix the dry ingredients together (flour, baking soda, baking powder, salt, and cinnamon). Set aside.
Beat the butter (room temperature) with a mixer on high speed until creamy then add the sugar and beat again. Add the eggs and the vanilla extract and beat on a medium speed. Add the mashed bananas and the yogurt and beat until creamy. Stir in the dry ingredients into the wet ingredients and stir until just combined (make sure not to over mix if you want a fluffy cake)
For the streusel, combine all streusel ingredients in a bowl, and then start layering the cake by layering half of the batter into your baking pan, then layer half of the streusel, repeat.
Bake for 45 minutes or until the centre of the cake is done. Allow cake to slightly cool for 10-15 minutes then cut into pieces and serve. It is recommended to consume this cake warm and within 3 days of baking.