Overnight Eggnog Coffee Cake makes a delicious holiday breakfast. The whole thing can be prepped the night before and then popped in the oven Christmas morning.
Combine all streusel ingredients in a small bowl. Mix with a fork until crumbly. Set aside.
In a medium bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
Use an electric mixer to beat butter and granulated sugar until light and creamy.
Beat in eggs one at a time and then rum extract.
With mixer on low, beat in eggnog and then sour cream.
Add flour mixture and beat on low until mixed in.
Transfer batter to a greased 9x13-inch baking dish.Sprinkle streusel on top.
Cover with plastic wrap and refrigerate overnight.Note: You can bake it right away if you choose. It will cook a little faster so check it after about 28 minutes.
Preheat oven to 350 degrees. Remove plastic wrap and bake for 33 to 38 minutes.
To make glaze, whisk together powdered sugar and eggnog. Drizzle on coffee cake.