Moist Apple Crumble Coffee Cake Recipe

Making the Crumble

Combine ¾  cup rolled oats, ½  cup brown sugar, ¼  cup flour, and 1  teaspoon ground cinnamon in a food‑processor. Pulse a few times, then add the cold ¼  cup butter. Pulse until the mixture resembles coarse crumbs—small butter pieces are essential for a crisp topping.

Preparing the Batter

1. Mix dry components. In a large bowl whisk together 1 ½ cups flour, ½ cup sugar, 2  teaspoons baking powder, and ¼  teaspoon salt. This ensures even leavening and prevents pockets of flour.
2. Combine wet ingredients. In a separate bowl, whisk the melted ½ cup butter, cooled coffee, beaten eggs, and vanilla extract until smooth. The coffee adds depth without making the batter too liquid.
3. Bring together. Create a well in the dry mixture, pour in the wet mixture, and gently fold with a spatula until just combined. Over‑mixing would develop gluten, leading to a dense cake.

Assembling the Cake

1. Layer the batter. Lightly grease a 9‑inch round cake pan. Spread half of the batter evenly on the bottom, creating a smooth base.
2. Add apple layer. Evenly distribute the tossed apple slices over the batter, allowing the syrup to soak into the cake as it bakes.
3. Top with remaining batter. Spoon the rest of the batter over the apples, smoothing gently—don’t press too hard; you want the apples visible.
4. Finish with crumble. Sprinkle the oat crumble evenly across the surface. The crumble should cover the batter completely for a uniform golden crust.

Baking and Cooling

Bake for 35‑40 minutes, or until a toothpick inserted into the center comes out clean and the crumble is a deep amber. Allow the cake to cool in the pan for 10 minutes, then transfer to a wire rack. Cooling lets the crumble set, preserving its crunch.