For the crumble topping (optional)
1/2 cup (70 g) all purpose gluten free flour (I used Better Batter)
1/4 teaspoon xanthan gum (omit if your blend already contains it)
3 tablespoons (40 g) packed light brown sugar
1/2 teaspoon ground cinnamon
1/8 teaspoon kosher salt
2 1/2 tablespoons (35 g) unsalted butter, melted and cooled
For the quick bread batter
2 cups (280 g) all purpose gluten free flour (I used Better Batter)
1 teaspoon xanthan gum (omit if your blend already contains it)
1/4 cup (36 g) cornstarch
3/4 teaspoon kosher salt
1 teaspoon baking powder
1/2 teaspoon baking soda
2 teaspoons apple pie spice (See Recipe Notes)
3/4 cup (150 g) granulated sugar
6 tablespoons (84 g) unsalted butter, at room temperature
2 eggs (100 g, weighed out of shell) at room temperature, beaten
2/3 cup (5 1/3 fluid ounces) buttermilk, at room temperature (See Recipe Notes)
5 ounces apple butter, homemade or store bought, at room temperature
For apple pie spice
To make your own apple pie spice, combine 4 teaspoons ground cinnamon + 1/2 teaspoon ground cardamom + 1/2 teaspoon freshly grated nutmeg + 1/4 teaspoon ground ginger + 1/8 teaspoon ground allspice.
For the buttermilk
If you’ve run out of buttermilk, you can use half (1/3 cup) milk and half (1/3 cup) plain yogurt. They can both be dairy-free if you can’t have dairy.
Preheat your oven to 350°F. Grease and line a standard 9-inch x 5-inch loaf pan and set it aside.
If you plan to use the optional crumble topping, you need to make it first so it has a chance to cool and solidify before using it. In a medium-size bowl, place the flour, xanthan gum, brown sugar, cinnamon, salt, and mix to combine, breaking up any lumps in the brown sugar. Add the melted butter, and mix to combine well. The mixture will be thick. Place the bowl in the refrigerator to chill for about 10 minutes or until firm (or the freezer for about 5 minutes) while you make the quick bread batter.
To make the quick bread batter, in a large bowl, place the flour, xanthan gum, cornstarch, salt, baking powder, baking soda, apple pie spice, and granulated sugar, and whisk to combine well. Create a well in the center of the dry ingredients, and add the butter, eggs, buttermilk, and apple butter, and mix to combine well. The batter will be very thick.
Scrape the batter into the prepared pan, pressing it into all corners of the pan. With wet fingers and/or a wet spatula, smooth the top of the batter into an even layer. Using a small, sharp knife, score the top of the loaf along the length in the center, about 1/4-inch deep. Remove the (optional) crumble topping from the refrigerator, and break it up into relatively small pieces with the tines of the fork. Sprinkle the top of the raw loaf evenly with the crumble topping and press gently to help the pieces adhere to the batter.
Place the loaf pan in the center of the preheated oven and bake until the top is domed and lightly golden brown in color, and a toothpick inserted in the center comes out with no more than a few moist crumbs attached, about 50 minutes. For the most even baking, rotate the pan one half turn halfway through baking. Remove the pan from the oven and allow to cool for 10 minutes before turning out onto a wire rack to cool completely. Slice and serve once cool.