1-Preheat and Prep Your Pan: First Step: Set oven to 350°F. Grease an 8×8-inch baking pan with butter or line with parchment paper, leaving overhang for handles. This prevents sticking and eases cutting. Pro tip: Parchment ensures clean edges for potluck presentation.

2-Melt and Mix the Base: Second Step: In a medium saucepan or microwave-safe bowl, melt ½ cup butter until fully liquid, about 1 minute on medium power. Stir in 1 cup packed brown sugar until smooth and glossy, roughly 2 minutes. The mixture thickens slightly, building that toffee base. Let cool 5 minutes to avoid cooking the egg later.

3-Incorporate Wet Ingredients: Third Step: Whisk in 1 egg and 1 tsp vanilla extract until fully combined. Add a pinch of salt. The batter turns creamy and pale. Use room-temp egg for even blending; cold ones cause lumps. This step takes 1 minute and sets the flavor foundation.

4-Add Dry Ingredients: Fourth Step: Sift in 1 cup flour and ½ tsp baking powder. Stir gently with a spatula just until no streaks remain, about 30 strokes. Overmixing toughens the texture, so stop early for maximum chew. Batter resembles thick cookie dough.

5-Fold in Mix-Ins: Fifth Step: Fold in 1 cup chocolate chips or chopped nuts evenly. Distribute by hand to prevent sinking. For even bars, sprinkle half in pan bottom before batter. This adds texture contrast perfect for sharing.

6-Bake to Perfection: Sixth Step: Spread batter evenly in prepared pan using offset spatula or back of spoon. Smooth top for uniform bars. Bake at 350°F for 25-28 minutes. Edges turn golden, center stays soft and slightly jiggly pull early for fudgy results. Rotate pan halfway for even browning.

7-Cool and Cut: Final Step: Cool in pan on wire rack 30 minutes, then lift out using parchment. Cut into 16 squares once fully room temp, about 1 hour total. Warm bars firm up for neat slices. Serve at potlucks plain or with scoops of ice cream. Store as below.