Preheat your oven to 350°F (175°C). Prepare a loaf pan by greasing it or lining it with parchment paper.

Combine the dry ingredients in a large bowl: whisk together the flour, baking powder, nutmeg, and sugar.

In another bowl, mix the wet ingredients: stir together the melted butter, eggnog, vanilla extract, and eggs until smooth.

Fold the wet mixture into the dry ingredients until just combined, being careful not to over-mix.

Prepare the crumb topping by combining the brown sugar, oats, cinnamon, and melted butter until crumbly.

Layer the batter and topping in the loaf pan: pour half of the batter, sprinkle with half of the crumb topping, add remaining batter, and scatter the rest of the topping on top.

Bake for about 50-60 minutes or until golden brown and a toothpick comes out clean.

Cool the bread slightly before slicing, and serve warm.