1. Preheat oven to 350°F (176°C). Prepare a 9 inch cake pan with a circle of parchment paper in the bottom and grease the sides.
2. To prepare the streusel, combine all the ingredients with the melted butter in a medium sized bowl and mix with a fork until all ingredients are incorporated and crumbly. Set aside.
3. To make the cake batter, beat the sugar and butter until light in color and fluffy, 3-4 minutes.
4. Add the sour cream and eggnog and mix until well incorporated. The batter may seem a little curdled, that’s ok.
5. Add the egg, egg yolk and vanilla extract and mix until smooth.
6. Combine the dry ingredients in a separate bowl.
7. Add the dry ingredients to the batter and mix until smooth.
8. Spread the batter evenly into the prepared cake pan.
9. Sprinkle the streusel evenly over the top of the cake.
10. Bake the cake for 40-45 minutes. The cake should be a nice golden color on top. It might still jiggle just a touch, but that’s ok. The streusel on top will firm as it cools.
11. Allow the cake to cool, then remove from the cake pan.
12. Combine glaze ingredients and whisk until smooth, then drizzle over the cake. Serve it warm or cool.