Peel and finely dice the apples. Toss them with dark brown sugar, cinnamon, salt, and lemon juice.

Cook the apples on the stove over low to medium heat for about 10 minutes until they are browned and caramelized.

Let them chill in the fridge.

Melt the butter in a pot over medium heat, stirring occasionally until it turns golden brown.

Cool the butter in the fridge for about 10 minutes.

In a bowl, whisk together the flour, baking soda, cream of tartar, cinnamon, salt, and cornstarch. Set aside.

In another bowl, whisk the cooled brown butter, dark brown sugar, white sugar, and vanilla until combined.

Add the egg and egg yolk, then whisk until smooth.

Gently fold in the caramelized apples.

Mix the dry ingredients into the wet ingredients, folding until just combined.

Cover the dough tightly and chill in the fridge for 2-3 hours.

Preheat the oven to 350F (175C) and line a baking sheet with parchment paper.

In a small bowl, mix the granulated sugar and ground cinnamon for coating.

Use a cookie scoop to shape the dough into balls and roll them in the cinnamon sugar mixture.

Place them 2-3 inches apart on the baking sheet.

Bake for 12-14 minutes. The edges should be golden and tops slightly puffy.

Let the cookies sit on the baking sheet for 5 minutes before transferring to a cooling rack.