Make the Cake: Preheat oven to 350. Spray a tube pan generously with nonstick cooking spray.
In a large bowl, beat together the butter and sugar until light and fluffy. Beat in eggs one at a time. Beat in eggnog, sour cream, nutmeg and vanilla extract.
In a separate bowl, whisk together flour, baking powder, baking soda, and salt.
Add half of the dry ingredient into wet ingredients and blend just until mostly combined. Add the rest of the dry ingredients and blend just until combined.
Spread batter into prepared pan. Tap pan on the counter to remove air bubbles. Set aside.
Meanwhile make the Crumb Topping: In a medium bowl blend sugars, spices and salt into melted butter until mixture becomes smooth. Add flour and combine thoroughly.
Crumble crumb mixture into big pieces over top of unbaked coffee cake.
Bake Coffee Cake for 35-45 minutes in preheated oven just until a cake tester inserted in the center of the cake comes out clean.
Cool on the rack for 10-15 minutes. Place a plate on top of the cake and flip the cake over onto the plate. Place a serving plate on the bottom of the cake and flip the cake over to right-side up. Cool cake completely before icing it.
Make Icing: Whisk together the butter and eggnog in a small saucepan over low heat. Bring mixture to a simmer and simmer for 2 minutes, whisking constantly. Cool slightly and whisk in powdered sugar until mixture is smooth with no lumps. Drizzle icing over completely cooled cake.