Beat butter and white sugar in a bowl with an electric mixer until light and fluffy, about 2 minutes.
Beat eggs and sour cream into butter mixture until smooth.
Whisk flour, baking powder, baking soda, nutmeg, and salt together in a bowl until thoroughly combined; stir into the sour cream mixture to make a batter.
Pour the batter into the prepared baking dish.
Mix the brown sugar, pecans, and cinnamon in a bowl; sprinkle the mixture over the batter.
Cover the baking dish with plastic wrap and chill 8 hours to overnight.
Preheat oven to 350 degrees F (175 degrees C).
Remove plastic wrap from the dish; bake until a toothpick inserted into the center of the coffee cake comes out clean, 35 to 40 minutes.
