1-First Step: Mise en place and cream butter. Cube 1 cup cold unsalted butter into ½-inch pieces straight from the fridge. In a stand mixer with paddle, beat with 1 cup light brown sugar and ½ cup granulated sugar on medium 2-3 minutes until fluffy and no lumps remain. Cold butter creates dense dough for levain cookies’ height. Scrape bowl often. This takes 5 minutes and sets up crispy edges.

2-Second Step: Mix in wet ingredients. Add 2 eggs one at a time, beating 30 seconds each. Mix in 1 ½ tsp vanilla extract. For vegan, use 6 tbsp aquafaba whipped to peaks. Batter may look curdled; that’s normal for copycat recipe texture. Keeps it soft inside.

3-Third Step: Combine dry ingredients. Whisk ½ cup cake flour, 1 ½ cups bread flour, 1 tsp cornstarch, ¾ tsp baking soda, ½ tsp salt in a bowl. For gluten-free, swap to 2 cups 1:1 blend. Gradually add to wet mix on low speed until just combined, 1 minute. Avoid overmixing to prevent tough bakery cookies.

4-Fourth Step: Fold in mix-ins. Gently fold 1 ¼ cups semi-sweet chocolate chips, 1 ¼ cups chopped walnuts, and optional 1 ¼ cups cookie dough or cake chunks. Use spatula for even distribution. Dough stays thick. Nut-free? Double chips or add oats. Takes 2 minutes.

5-Fifth Step: Chill dough. Cover bowl, refrigerate 30 minutes. Chilling firms butter for tall levain chocolate chip crush cookies levain. If rushed, 15 minutes works, but longer yields better shape.

6-Sixth Step: Scoop and bake. Scoop 6-oz balls (about ⅔ cup) onto parchment-lined sheets, 3-4 per sheet. Flatten slightly to 4 inches wide. Bake at 400°F for 9-11 minutes. Edges golden, centers pale and soft with cracks. High heat mimics bakery ovens. For smaller 2-oz cookies, bake 8-10 minutes, yields 16-20.

7-Final Step: Cool and serve. Cool on sheet 10 minutes, then rack. They firm while staying gooey. Serve warm for peak levain bakery copycat recipe enjoyment. Pair with milk. Total time: 1 hour. Store airtight.