Preheat and Prep: Preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone baking mats.

Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking soda, salt, and cinnamon. Set aside.

Cream Butter and Sugars: In a large bowl, use an electric mixer to cream the softened butter, granulated sugar, and brown sugar until light and fluffy, about 2-3 minutes.

Add Wet Ingredients: Dissolve the cornstarch in the milk, then add it to the butter mixture along with the vanilla extract. Mix until well combined.

Combine Dry and Wet Ingredients: Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Avoid overmixing.

Fold in Mix-Ins: Using a spatula, gently fold in the chocolate chips and chopped pecans until evenly distributed throughout the dough.

Scoop and Bake: Drop heaping tablespoons of dough onto the prepared baking sheets, spacing them about 2 inches apart. Lightly press down on each dough ball to slightly flatten it. Sprinkle a pinch of flaky sea salt on top of each cookie.

Bake: Bake for 9-11 minutes, or until the edges are lightly golden but the centers are still soft. If baking two sheets at once, rotate them halfway through the baking time for even cooking.

Cool: Let the cookies cool on the baking sheet for 5 minutes, then transfer them to a wire rack to cool completely.