Step 1

Preheat oven to 350º F and line a 9x13-inch baking dish with parchment paper.

Step 2

Cream together butter and sugars in a large bowl or mixer until fluffy and lightened in color.

Step 3

Add in oats, flour and walnuts, then mix in baking soda, cinnamon, salt, nutmeg and allspice until combined.

Step 4

Pour 1/2 crust mixture into lined baking dish and use your hands or a flat-bottomed surface to press crust into an even layer.

Step 5

Place baking dish in oven and bake for 10 minutes, or until lightly browned.

Step 6

While crust is pre-baking, whisk together sour cream, sugar, egg, honey and vanilla extract in a large bowl, then mix in shredded apples.

Step 7

Pour mixture over baked bottom crust and spread into an even layer, then top with remaining crumble mixture, pressing gently, so it adheres to filling layer.

Step 8

Place in oven and bake for 35 minutes, or until topping is golden brown. Cover with aluminum foil if topping is browning too quickly.

Step 9

Remove from oven and let cool completely before serving.

Step 10

Enjoy!