Prep the pans: Line two large baking sheets with parchment paper and set them aside.

Preheat the oven: Set your oven to 410°F (yes, this high temperature is key for that thick, gooey center).

Cream the butter & sugars: In a stand mixer with a paddle attachment, whip the butter for 1 minute until fluffy. Add the brown sugar and granulated sugar, then cream for 3 minutes on high until fully combined.

Add wet ingredients: Scrape down the sides of the bowl. Mix in the vanilla, peach flavoring (if using), and eggs until smooth.

Combine dry ingredients: Add cinnamon, cornstarch, baking soda, salt, and flour. Mix on low speed until just combined—do not overmix.

Fold in the goodies: Reserve about ⅛ cup of cinnamon chips and 1 tablespoon of peach cubes for topping. Gently fold the oats, cinnamon chips, and remaining chopped peaches into the dough.

Shape the cookies: Divide dough into 8 large (baseball-sized) balls. Place 4 cookies per baking sheet. Press the reserved chips and peach cubes onto the tops for a beautiful finish.

Bake & cool: Bake for 9–10 minutes until the cookies are slightly golden on the edges but still gooey in the center. Let cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.