• Preheat oven to 350F. Grease a 9x13-inch baking dish with non-stick cooking spray; set aside.
• In a large mixing bowl, whisk together the flour, sugar, baking powder, nutmeg, and salt; set aside.
• In a medium mixing bowl, combine the mashed sweet potatoes and milk together, then mix in the beaten eggs and vanilla extract.
• Add the wet mixture to the dry mixture and stir just until combined. Add the melted butter and fold in until fully incorporated.
• Pour the batter into the prepared baking dish.

Crumble Topping

• In a medium mixing bowl, combine the brown sugar, flour, and cinnamon for the crumble topping. Cut in the 1/2 cup (1 stick) softened butter until the mixture is crumbly. Sprinkle the topping all over the cake batter in the baking dish and use a butter knife to swirl it into the cake batter just a little bit so some of the topping settles down into the cake and some is on top.
• Bake the cake at 350F for 35-40 minutes, or until a toothpick inserted into the center comes out clean.

Maple Glaze

• In a medium mixing bowl, combine the ingredients for the glaze. Pour the glaze over top of the cake while it is still warm.
• Slice and serve warm or at room temperature.