Oven 350 deg F

Coat a 9 inch springform pan with cooking spray. Toss raisins and rum in a small bowl and let stand. Whisk flour, nutmeg, and salt in another bowl.

Mash sweet potato in a large bowl (you should have about 1-3/4 cups). Add eggs;beat with an electric mixer on medium until combined. Add coconut milk, 1 cup brown sugar and butter; beat until combined. Stir in the dry ingredients until evenly moistened. Stir in the raisins and any remaining rum. Spread the batter in the prepared pan.

Combine topping ingredients and sprinkle on top of cake.

Bake the cake until a knife inserted into the center comes out clean, 1 to 1-1/4 hours. Let cool in the pan for 10 minutes. Run a knife around the edge of the pan and remove the side ring. Let cool at room temp for 1 hour, then refrigerate until cold, about 3 hours.