Preheat oven to 350 degrees. Coat a 9x13 cake pan with nonstick cooking spray. Set aside.
In the bowl of a stand mixer or a large bowl with an electric mixer, beat butter and sugar until fluffy. Beat in the eggs, one at at time, until smooth.
In a separate bowl, whisk the dry ingredients: flour, baking soda, baking powder, salt, cinnamon and nutmeg.
Beat the flour mixture into the wet ingredients alternately with the buttermilk. Pour the batter into the cake pan.
Make the crumb topping: combine all ingredients in a small bowl. Sprinkle over the cake batter. Bake 40 minutes. Cool completely in the pan.
Make the glaze: whisk all ingredients together in a small bowl. Drizzle over the cooled cake before serving.