Preheat oven to 350°F (180°C). Line baking sheets with parchment paper or silicone baking mats. Set aside.
Combine the flour, baking soda and salt in a medium sized bowl and set aside.
Cream the butter and sugars together in a large mixer bowl on medium speed until light in color and fluffy, 2-3 minutes. You should be able to see the change in color happen and know it’s ready.
Add the egg yolk and mix until well combined.
Add the applesauce and vanilla extract and mix until well combined.
Add the dry ingredients and mix until the dough is well combined. It will be thick. Do not over mix. Once it’s combined, use a rubber spatula to help it come together to form a more cohesive ball.
Create cookie dough balls of about 6 tablespoons (105g) of cookie dough per ball. You should get 8 balls.
Place the cookie dough balls onto the prepared baking sheets. I baked 4 cookies at a time. Press the balls down a bit (I used underside of a cup). They should be a little more than 2 ½ inches in diameter. They will spread a good bit.
Bake the cookies for 12-15 minutes or until the cookies look done and are just about to brown on the edges.
Allow the cookies to cool for 5-10 minutes, then move to a cooling rack to cool completely.
While the cookies cool, make the apples. Combine the apples, lemon juice and water in a microwave-safe bowl and heat in 30 second increments, stirring between each, until apples are fork-tender or at your desired tenderness. It could take 3-5 minutes, depending on the size of your diced apples. Set aside to cool to about room temperature.
To make the streusel, add the sugar, flour and cinnamon to a medium-sized bowl.
Cut the butter into the flour mixture until the butter is fully incorporated and the mixture is crumbly. Set aside.
To make the brown sugar glaze, combine the powdered sugar, brown sugar, cinnamon, nutmeg, vanilla extract and 5 tablespoons of heavy cream. Whisk together until well combined. Add additional heavy cream as needed.
Spread 1-2 tablespoons of the glaze onto each cookie.
Divide the apples evenly between the cookies, about 1-2 tablespoons each.
Sprinkle the streusel onto the cookies, dividing it evenly between the cookies.
