📖 Instructions

1. Preheat your oven to 350°F (175°C). Grease and flour a 9-inch square baking pan. Or, if you're feeling fancy, use a springform pan. Makes it look extra impressive!
2. In a large bowl, whisk together the flour, baking powder, baking soda, salt, and cinnamon. Make sure there aren't any lumps of baking powder hiding in there. Nobody wants a bite of pure baking powder!
3. In a separate bowl, cream together the butter and sugar until light and fluffy. This might take a few minutes, so don't rush it. It's worth the effort!
4. Beat in the eggs one at a time, then stir in the vanilla extract. If your eggs are cold, let them sit in warm water for a few minutes first. They'll incorporate better into the batter.
5. Gradually add the dry ingredients to the wet ingredients, alternating with the sour cream, beginning and ending with the dry ingredients. Mix until just combined. Be careful not to overmix! Overmixing can lead to a tough cake, and nobody wants that.
6. Spread half of the batter into the prepared pan. It might be a little thick, but that's okay. Just do your best to spread it evenly.
7. In a medium bowl, combine the peeled, cored, and chopped apples with the brown sugar, cinnamon, and nutmeg. Toss to coat. I like using a mix of Granny Smith and Honeycrisp apples for the best flavor and texture.
8. Sprinkle the apple mixture over the batter in the pan. Don't be shy – load it up with apples!
9. Drop spoonfuls of the remaining batter over the apple mixture. It doesn't have to be perfect – a little bit of apple peeking through is totally fine.
10. In a small bowl, combine the flour, brown sugar, and cold butter for the streusel topping. Cut the butter in with a pastry blender or your fingers until the mixture resembles coarse crumbs. The colder the butter, the better the streusel!
11. Sprinkle the streusel topping evenly over the batter. Now, this is where the magic happens!
12. Bake for 45-50 minutes, or until a wooden skewer inserted into the center comes out clean. If the top starts to get too brown, tent it with foil. Ovens can be so temperamental, can't they?
13. Let the cake cool in the pan for 10-15 minutes before serving. Or, if you used a springform pan, release the sides and let it cool completely on a wire rack. Serve warm and enjoy! A scoop of vanilla ice cream on top? Highly recommended.