Preheat oven to 350°F/160°C. Grease a 10-inch circular pan, line with parchment paper. Sift flour and baking powder into a bowl.
Cream butter and sugar until pale and fluffy. Add egg yolks gradually, mixing well. Blend in yogurt. Add vanilla, cinnamon, and nutmeg.
Cream butter and sugar until pale and fluffy. Add egg yolks gradually, mixing well. Blend in yogurt. Add vanilla, cinnamon, and nutmeg.
Mix ground cinnamon, melted butter, pecans, and caster sugar until lumpy. Spread this mixture evenly on top of the batter.
Pour batter into pan, level the top. Bake for 50-55 minutes, until a skewer comes out clean. Let it rest for 20 minutes before removing the ring.
After cooling, dust with powdered sugar if desired. Slice, serve, and savor the deliciousness of your homemade cinnamon apple cake! Enjoy!