1-First Steps: Mise en Place and Oven Prep
Preheat your oven to 325°F (160°C) and line baking sheets. Measure and set out all ingredients: tahini, butter, sugars, egg, egg yolk, vanilla, flour, baking soda, salt, and chocolate chunks. Chilling chocolate briefly helps create melty pockets without excessive spreading.

2-Creaming and Mixing: In a large bowl, beat butter, tahini, granulated sugar, and brown sugar on medium speed until fluffy, about 2-3 minutes. Add egg, egg yolk, and vanilla; mix another minute, scraping the bowl occasionally. This step integrates flavors and creates a smooth base for your Tahini Chocolate Chunk Cookies.

3-Combining Dry Ingredients: In a separate bowl, whisk together flour, baking soda, and kosher or sea salt. Add dry ingredients to the mixer on low speed until just combined. Gently fold in chocolate chunks to keep them intact for those gooey bites.

4-Refrigeration and Shaping: Cover dough and refrigerate overnight or at least several hours to improve texture and flavor. Form dough into rounds: 1 1/2-inch for small cookies or 2-inch for larger ones, placing them 3 inches apart on lined baking sheets.

5-Baking and Finishing: Bake one sheet at a time on the middle rack: about 12 minutes for small cookies, 14-15 minutes for larger, until edges are golden brown but centers are still pale. Remove from oven and sprinkle immediately with flaky sea salt. Cool on the baking sheet before transferring.