Banana Chocolate Chip Crumb Cake 
Adapted from Sally's Baking Addiction
Note: This recipe can be halved and baked in a 20cmx20cm square pan (8-9inch)
Serves 15 Prep Time: 20 minutes Baking: 50 minutes

Cake:
360g (3 cups) plain flour
3/4 tsp ground cinnamon
1 1/2 tsp baking soda
1 1/2 tsp baking powder
Pinch of salt
150g unsalted butter, softened at room temperature
190g white sugar
2 eggs
1 tsp vanilla extract
3 cups of mashed (very ripe) banana (about 5 medium bananas)
1/2 cup plain Greek yogurt

Streusel:
1 tbsp ground cinnamon
100g brown sugar
5 scotch finger biscuits, crushed
A handful of dark chocolate chips (to finish)

1. Preheat oven to 170 degrees C. Grease and line a 23cmx16cm baking dish with parchment paper, and set aside.
2. In a medium  bowl, mix together the flour, ground cinnamon, baking soda, baking powder, and salt. Set aside.
3. With an standing mixer or hand-held electric whisk, beat the softened butter at medium speed for 2 minutes until light.
4. Add in the white sugar, and cream together for an additional 2 minutes at medium speed, until light and fluffy.
5. Add in the eggs, one at a time, beating briefly after each addition. Mix in the vanilla extract as well.
6. Add in the mashed banana and yogurt, and mix for a few seconds until the mixture has combined. It will be quite liquid-y at this point- that's okay.
7. Add in the flour mixture prepared in step 2 and mix at low speed until just combined. Do not overmix.
8. In a small bowl, combine the streusel ingredients: the cinnamon, sugar and crushed biscuits.
9. Transfer half the cake batter into the prepared dish. Top it evenly with half the streusel mix. Repeat with remaining cake batter and streusel.
10. Bake for approx. 50 minutes or until a skewer inserted into the centre of the cake comes out clean or with just a few crumbs attached to it. If the top is browning too quickly, place some foil over the cake at the 20 minute mark.
11. As soon as the cake is done and is removed from the oven, sprinkle chocolate chips on top.
12. Let the cake cool for 15 minutes before slicing and serving.

-Cake is good for up to 4 days sealed in an airtight container.