Preheat your oven to 350°F (175°C) and grease a loaf pan (9x5 inches).
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg until well combined.
In a large mixing bowl, beat the softened butter and granulated sugar together with an electric mixer until light and fluffy, about 2-3 minutes.
Add the eggs, one at a time, mixing until thoroughly incorporated. Pour in the vanilla extract and mix until combined.
Mix in the sour cream until the batter is smooth.
Gradually add the dry ingredients to the wet mixture, mixing gently until no flour streaks remain.
Pour half the batter into the prepared loaf pan. Sprinkle half of the brown sugar on top, then top with the remaining batter. Finish with the rest of the brown sugar and a sprinkle of cinnamon.
Bake in the preheated oven for 50-60 minutes, or until a toothpick inserted in the center comes out clean.
Allow the bread to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely. Slice and serve once cooled.
Notes
Serve the slices warm, with a dollop of whipped cream or a drizzle of caramel sauce for an extra indulgent treat!