Preheat the oven to 350º F. Butter an 8 or 9-inch cake pan and line it with a circle of parchment paper.
In a medium bowl, whisk together the 1 ¾ cups gluten free flour, 1 ½ teaspoon baking powder, and ½ teaspoon fine sea salt.
In a large bowl, cream the ½ cup unsalted butter then add the 1 cup granulated sugar and beat until light and fluffy. Beat in the 2 large eggs one at a time, then beat in the 1 teaspoon pure vanilla extract.
With the mixer on low, stir half of the flour mixture into the butter mixture until just combined. Stir in the ½ cup full fat plain yogurt until just combined, then the rest of the flour, scraping down the sides and bottom of the bowl as needed.
Grease the parchment paper with the remaining 3 tablespoons unsalted butter, then evenly arrange the 3-4 large apples of choice so that the slices cover the bottom of the pan with no gaps. Sprinkle the apples with ½ teaspoon ginger and drizzle them with 1 tablespoon maple syrup.
Gently spread the batter over the apples, and let it rest for 15 minutes. Then bake the cake until the top is golden and a toothpick inserted near the center comes out clean, or with a few moist crumbs, 35-45 minutes. Remove from oven and let cake cool completely in pan on a rack, then invert onto a serving platter and peel away the parchment. Serve the cake at room temperature.
Notes
What size pan? This depends on your preferred cake-to-fruit ratio. I like a nice, thick cake, so I tend to always use an 8-inch cake round. However, for a slightly less-thick cake, a 9-inch cake round will result in a bit of a thinner cake (and, more servings!).
Apple type: Yes, again I used apples from my tree (Gravensteins, like in my gluten free apple cake), and I will always advocate for using what you have growing on your tree or what you can find at your local farmers' market. But in general, some of the best apples for baking include Honeycrisp, Pink Lady, and Braeburn.
Add almond flour - I find this cake to be plenty moist as the recipe is written, but to stretch it even further, add ½ cup of almond flour for ½ cup of the gluten-free flour for extra protein and moisture.
Dairy-free - Make this cake dairy-free by subbing non-dairy butter for the butter and a non-dairy yogurt for the yogurt.
Swap milk - If you don't have yogurt in the fridge, go ahead and swap whole or 2% milk (or non-dairy milk) for the yogurt.
Spices - I've made this cake using ground ginger, cinnamon, and cardamom, and I heartily endorse any of these spices! You could also do a blend. The ground spice adds a subtle bit of warmth to the apples. Conversely, you could leave off the spice if you wish for a plainer cake.