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 use your fingers to combine 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 and 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 and 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.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.