Creating Caramel Apple Crumb Cake is a straightforward process. Just follow these steps to ensure success:

1. Preheat Oven: Preheat your oven to 350°F (175°C). Grease and flour a 9×13 inch baking pan.
2. Mix Dry Ingredients: In a large bowl, whisk together the flour, granulated sugar, baking powder, baking soda, salt, and ground cinnamon.
3. Cream Butter and Sugar: In another bowl, beat the softened butter and remaining granulated sugar until light and fluffy.
4. Add Eggs and Sour Cream: Mix in the eggs, one at a time, followed by the sour cream. Blend until smooth.
5. Combine Mixtures: Gradually add the dry ingredients to the wet mixture, stirring until just combined.
6. Fold in Apples: Gently fold in the diced apples, ensuring they are evenly distributed throughout the batter.
7. Prepare Crumb Topping: In a separate bowl, mix together brown sugar, rolled oats, ground nutmeg, and cold cubed butter. Use a pastry cutter or your fingers to combine until crumbly.
8. Assemble the Cake: Pour the batter into the prepared baking pan. Evenly spread the crumb topping over the batter.
9. Bake: Place in the oven and bake for 40-45 minutes, or until a toothpick inserted in the center comes out clean.
10. Cool and Drizzle: Remove from the oven and allow the cake to cool in the pan for about 15-20 minutes. Drizzle with caramel sauce before serving.

Follow these steps carefully, and you will have a beautiful Caramel Apple Crumb Cake to share with friends and family!