1. Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
2. In a medium bowl, whisk together the flour, baking soda, and salt; set aside.
3. In a larger bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy, about 3-4 minutes.
4. Add the egg and vanilla extract to the butter mixture, mixing until well combined.
5. Gradually add the dry ingredients to the wet ingredients, mixing until just incorporated.
6. Fold in the diced apples and cinnamon until evenly distributed throughout the dough.
7. For the crumb topping, combine the flour, brown sugar, melted butter, and cinnamon in a small bowl. Mix until crumbly.
8. Drop rounded tablespoons of cookie dough onto the prepared baking sheet, spacing them about 2 inches apart.
9. Sprinkle a generous amount of crumb topping over each cookie.
10. Bake for 12-15 minutes, or until the edges are lightly golden. Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.

The moment you take these cookies out of the oven, you’ll be transported to a place of comfort and love—much like the kitchen of my childhood. Remember, the key to these cookies is not to overmix the dough, keeping the texture just right.