Apple Crumble Coffee Cake

Recipe View Gather all ingredients.

Recipe View Preheat the oven to 350 degrees F (175 degrees C). Butter a 9x12-inch baking dish generously. (5 minutes)

Recipe View Whisk flour, baking powder, baking soda, and salt together in a bowl. Set aside. (3 minutes)

Recipe View Combine walnuts, brown sugar, white sugar, melted butter, cinnamon, and salt in a bowl. Mix until walnuts and sugar are thoroughly coated with butter. (5 minutes)

Recipe View Cream sugar and butter together in another bowl with a spatula until well blended. (5 minutes)

Recipe View Add 1 egg and whisk until mixture is smooth. (2-3 minutes)

Recipe View Whisk in second egg until thoroughly incorporated. Add yogurt and vanilla; whisk together. (3 minutes)

Recipe View Add dry flour mixture to wet ingredients; whisk just until flour disappears. Do not overmix. (2 minutes)

Recipe View Remove cores from apples. Cut across into 1/8- to 1/4-inch slices. Stack up a few slices, make a cut down the center, and dice across into cubes. (10 minutes)

Recipe View Add to cake batter, folding in with a spatula until just combined. (2 minutes)

Recipe View Spread 1/2 of the batter evenly into the bottom of the prepared baking dish. Scatter 1/2 of the crumble mixture evenly over the top. (5 minutes)

Recipe View Top with the rest of the batter in dollops. Spread carefully to evenly distribute, trying not to disturb the crumbs. (5 minutes)

Recipe View Top with the rest of the crumb mixture. Press crumbs into the batter very gently. (3 minutes)

Recipe View Bake in the center of the preheated oven until a toothpick or bamboo skewer inserted into the center comes out clean. (40 minutes)

Recipe View Let cool to room temperature before slicing and serving. (30 minutes)