Preheat your oven to 350°F (175°C). Line two large baking sheets with parchment paper or silicone baking mats to help the cookies bake evenly and prevent excess spreading.

In a medium bowl, whisk together the all-purpose flour, baking soda, and fine sea salt until well combined. Set aside.

In a large mixing bowl, beat the softened butter, packed light brown sugar, and granulated sugar together with a hand mixer or stand mixer on medium speed for 2–3 minutes, until light and fluffy and slightly lighter in color.

Add the eggs one at a time, mixing on low to medium speed after each addition just until combined. Add the vanilla extract and mix again. Scrape down the sides and bottom of the bowl so everything is evenly mixed, but do not overbeat.

With the mixer on low, gradually add the flour mixture to the wet ingredients. Mix just until no streaks of dry flour remain. The dough will be thick and a bit sticky. If needed, finish folding with a spatula to avoid overmixing.

Use a spatula to fold in the semisweet chocolate chips and the mini chocolate chips or chopped dark chocolate, if using. Make sure the chocolate is evenly distributed throughout the dough.

Cover the bowl and chill the dough in the refrigerator for 30–45 minutes. This helps control spreading and deepens the flavor. If chilled longer, let the dough sit at room temperature for a few minutes until scoopable.

Use a medium cookie scoop (about 1 1/2 tablespoons of dough) or roll the dough into balls about 1 1/2 inches wide. Place on the prepared baking sheets, spacing at least 2 inches apart. For bakery-style tops, press a few extra chocolate chips into the top of each ball, then sprinkle lightly with flaky sea salt if desired.

Bake one sheet at a time for 9–11 minutes, or until the edges are lightly golden and the centers still look a bit soft and puffy. For softer cookies, remove closer to 9 minutes; for slightly firmer cookies, bake up to 11 minutes. The cookies will continue to cook on the hot baking sheet.

Let the cookies cool on the baking sheet for 5 minutes, then transfer them to a wire rack to cool completely. This resting time helps set the chewy texture.