- With the rack in the middle position, preheat the oven to 350°F (180°C). Generously butter an angel food cake pan.
- In a bowl, combine all the dry ingredients. Stir in the butter and combine with your fingers until crumbly. Set aside.
- In another bowl, combine the flour, baking powder and baking soda.
- In a large bowl, cream the butter and brown sugar with an electric mixer. Add the eggs and beat until smooth. Add the dry ingredients alternating with the milk. Using a spatula, stir in the squash. Spoon half of the batter into the cake pan and sprinkle with half of the streusel. Repeat with the remaining batter and streusel.
- Bake for 1 hour 10 minutes or until a toothpick inserted into the centre of the cake comes out clean. Let cool on a wire rack. Run the blade of a knife between the cake and the pan. Unmould.
For 1 1/2 cups of coarsely mashed cooked squash, roast a small butternut squash, cut in half and seeded, cut side down, at 375°F (190°C) for about 45 minutes or until tender.