Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan (or line it with parchment paper for easy removal).
In a large mixing bowl, thoroughly whisk together 2 cups of all-purpose flour, 1 teaspoon of baking soda, ½ teaspoon of baking powder, ½ teaspoon of kosher salt, 1.5 teaspoons of ground cinnamon, ½ teaspoon of ground nutmeg, ¼ cup of granulated sugar, and ¼ cup of packed light brown sugar. Use your fingers or the whisk to break up any stubborn clumps of brown sugar until the mixture is completely uniform.
Make a small well in the center of your dry mix. Pour in the wet elements directly: 1 cup of unsweetened applesauce, ½ cup (1 stick) of slightly cooled melted unsalted butter, ¼ cup of sour cream or full-fat Greek yogurt, and 2 large eggs.
Using a wooden spoon or a flexible spatula, gently stir everything together just until the dry flour disappears and a thick batter forms. A few small lumps are perfectly fine! Avoid overmixing here, as over-activating the gluten will make the bread turn out tough instead of tender.
Scrape the batter into your prepared loaf pan and smooth out the surface with your spatula. In a tiny cup, mix together your topping ingredients: 1 tablespoon of granulated sugar, ½ teaspoon of ground cinnamon, and 1 tablespoon of finely chopped pecans.
Sprinkle this mixture evenly across the entire top of the batter. Bake on the center rack for 50 to 60 minutes, or until a toothpick inserted into the center comes out clean or with just a few moist crumbs attached.
Let the bread cool in the pan for 10 minutes to allow the crumb to set, then transfer it to a wire rack to cool completely before slicing and serving.
