1-First Step: Preheat and Prep Pan Preheat oven to 375°F. Grease a 13×18-inch jelly roll pan with butter or non-stick spray. Line with parchment for easy release leave overhang for handles. This prevents sticking and ensures clean slices. Pro tip: Cold pan yields thicker cookies; room temp spreads more.

2-Second Step: Cream Butter and Sugars In a large bowl, beat 1 cup softened butter, 1 cup brown sugar, and ½ cup granulated sugar with electric mixer on medium 2-3 minutes until light and fluffy. Scrape sides often. This incorporates air for tenderness. If no mixer, use sturdy spoon takes longer but works.

3-Third Step: Add Eggs and Vanilla Beat in 2 eggs one at a time, then 2 tsp vanilla extract. Mix until fully combined, about 1 minute. Batter may look curdled; normal. Eggs provide moisture and emulsify fats for even bake.

4-Fourth Step: Combine Dry Ingredients In separate bowl, whisk 2¼ cups flour, 1 tsp baking soda, and 1 tsp salt. Gradually add to wet mixture on low speed until just combined no overmixing to avoid tough cookies. Dough thickens quickly.

5-Fifth Step: Fold in Chocolate Chips Gently fold 2 cups chocolate chips with spatula. Reserve ¼ cup for topping. Chill dough 30 minutes optional for thicker result. Similar to this sheet pan cookie cake approach, even distribution matters.

6-Sixth Step: Spread Dough Evenly Transfer dough to pan. Use offset spatula or wet hands to spread uniformly ¼-inch thick. Corners fill last press gently. Sprinkle reserved chips and pinch sea salt. Uniformity bakes evenly.

7-Seventh Step: Bake to Perfection Bake 18-22 minutes. Edges golden, center set toothpick clean with moist crumbs. Rotate halfway if oven uneven. Overbaking dries; underbaking gooey. Cool in pan 10 minutes, then wire rack fully.

8-Eighth Step: Make and Apply Frosting Beat 8 oz softened cream cheese, ¼ cup butter, 3 cups powdered sugar, 1 tsp vanilla until smooth. Spread over cooled cake. Chill 30 minutes to set. Skip for unfrosted bars.

9-Final Step: Slice and Serve Cool completely 2 hours. Cut into 24 squares with sharp knife. Serve room temp. Store as below. Pairs with milk, ice cream, or fruit. Troubleshooting: Soggy? Bake longer. Crumbly? More butter next time.