Prep your pans: Line two baking sheets with parchment paper. This prevents sticking and encourages even browning.

Mix dry ingredients: In a medium bowl, whisk together flour, baking soda, baking powder, and salt. Set aside.

Cream butter and sugars: In a large bowl, beat the butter, brown sugar, and granulated sugar on medium speed until light and slightly fluffy, about 2–3 minutes. Don’t overdo it—you want some structure without whipping in too much air.

Add egg, yolk, and vanilla: Beat in the egg, then the yolk, then vanilla until smooth. Scrape the bowl so everything’s evenly mixed.

Combine wet and dry: Add the dry ingredients to the wet. Mix on low just until the flour disappears. Stop as soon as you don’t see streaks to avoid tough cookies.

Stir in chocolate (and nuts if using): Fold in the chocolate chips or chunks and nuts with a spatula. Save a small handful of chocolate to press on top later for a bakery look.

Chill the dough: Cover and refrigerate for at least 30–45 minutes (up to 24 hours). Chilling is key for thicker cookies and richer flavor.

Preheat the oven: Heat to 350°F (175°C). Let the dough warm slightly if it’s very hard, about 10 minutes.

Scoop and shape: Scoop generous 2-tablespoon portions (about 45–55 g each). For bakery-style height, shape into slightly taller mounds rather than perfect balls. Place 2 inches apart on the sheet.

Bake: Bake 10–12 minutes, rotating the pan once. The edges should be set and light golden, but the centers should look slightly underdone. They’ll finish setting as they cool.

Top and cool: Immediately press a few reserved chips on top for looks. If you like, sprinkle with flaky salt. Let cookies cool on the sheet 5–7 minutes, then transfer to a rack.

Enjoy at peak: They’re best slightly warm when the chocolate is soft and the centers are chewy.