To a separate bowl, add flour, cinnamon, ginger, nutmeg, allspice, cardamom and salt. Mix well.
Melt 8 tbsp of butter and add it to the flour mixture. mix until a crumb starts to form and everything is moistened with the melted butter. Set aside.
Into a large bowl, add butter and sugars. Cream together until light and fluffy.
Add room temp egg and mix well. Then add vanilla extract and mix.
Add 1 cup of flour and mix. Then add 1 cup of milk and sour cream and mix well. Then add the other cup of flour along with salt, baking soda, and baking powder. Mix until just combined. Do not over mix or the muffin will be tough.
To a 9×9 baking dish, add parchment paper. Pour half the batter into the dish, use a spatula to spread the batter out evenly. Top with the seasoned diced apples. Pour the rest of the batter on top and use a spatula to spread it out evenly.
Add the crumb topping on top of the batter and bake at 350℉ for 45 mins – 1 hour, or until a knife comes out clean.
***These can also be made into muffins, by adding some batter to the bottom of each liner, add the apples, then more batter, top with crumb and bake at 350℉ for 25-30 mins or until a knife comes out clean.