Preheat your oven to 350°F (175°C). Grease and flour a 9x5-inch loaf pan.
In a medium bowl, whisk together the flour, baking soda, salt, cinnamon, nutmeg, and ginger. Set aside.
In a large bowl, beat the softened butter and granulated sugar until creamy and light in color, about 2-3 minutes.
Add the pumpkin puree, eggs, and vanilla extract to the butter mixture, beating until fully incorporated.
Gradually mix in the dry ingredients, alternating with the sour cream (or yogurt), starting and ending with the dry ingredients. Stir until just combined.
In a small bowl, combine the brown sugar and cinnamon.
Pour half of the batter into the prepared loaf pan. Sprinkle half of the cinnamon-sugar mixture evenly over the batter. Add the remaining batter and top with the rest of the cinnamon-sugar mixture.
Use a knife or skewer to swirl the cinnamon-sugar through the batter for a marbled effect.
Bake for 55-60 minutes, or until a toothpick inserted into the center of the bread comes out clean.
Let the bread cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.