Ingredients
Equipment
Method
- Step 1 — Prepare the oven and pan: Set the oven rack to the middle position and preheat to 350°F (175°C). Line a 9x13 inch (23x33cm) light-colored aluminum baking pan with parchment paper, leaving a 2-inch overhang on both long sides, and anchor the parchment with a small amount of butter or non-stick spray underneath.
- Step 2 — Combine butter and sugar: Pour the melted and cooled butter (227g) into a large mixing bowl, add the packed brown sugar (300g), and stir with a silicone spatula for about 1 minute until fully combined, smooth, and glossy with no dry sugar pockets remaining.
- Step 3 — Add eggs and vanilla: Add the room-temperature eggs one at a time, stirring fully after each addition, then add the pure vanilla extract (2 teaspoons) with the second egg and stir for 30 seconds until the batter is smooth, slightly lighter in color, and uniform with no visible egg streaks.
- Step 4 — Fold in dry ingredients: Add the all-purpose flour (240g), old-fashioned rolled oats (180g), baking soda (1 teaspoon), and fine sea salt (½ teaspoon) to the bowl and fold with a silicone spatula using slow, wide strokes for 15–20 folds until no dry flour streaks remain and the oats are evenly distributed — stop the moment the flour disappears and do not mix further.
- Step 5 — Add chips and fill pan: Fold in 1¾ cups (298g) of the semi-sweet chocolate chips with 8–10 strokes, transfer the batter to the prepared pan, spread into an even layer pressing into the corners, then scatter the reserved ¼ cup (43g) of chips across the surface and press lightly with the flat of your palm to anchor them.
- Step 6 — Bake: Bake on the middle rack at 350°F (175°C) for 22–26 minutes, starting the visual check at 22 minutes — pull the pan when the edges are set and deep golden-brown, the surface looks matte and dry across the full pan, and the center has the faintest soft give when nudged.
- Step 7 — Cool and cut: Set the pan on a wire cooling rack and leave undisturbed for a minimum of 2 hours, then use the parchment overhang to lift the slab onto a cutting board, refrigerate for 30 minutes, and cut into 16 bars (4 columns by 4 rows) with a sharp knife wiped clean between each cut.
Notes
Oats: Old-fashioned rolled oats only — quick oats dissolve into batter and produce a pasty bar with no visible oat texture. Not substitutable.
Butter: Must be melted and cooled to room temperature before mixing — warm butter cooks the eggs and produces a greasy, dense bar.
Chocolate chips: Semi-sweet 45–55% cacao — milk chocolate is sweeter and melts differently; bittersweet produces a less sweet bar. Both work but change flavor balance.
Do not cut before 2 hours of cooling — centers are still setting and will collapse when the knife goes through.
Make-ahead: Bake fully, cool 2 hours, store uncut at room temperature overnight. Cut Day 2 after a 30-minute refrigerator chill for cleanest edges.
Freeze baked: Wrap each bar individually in plastic wrap, then store in a freezer bag up to 2 months. Thaw at room temperature 45 minutes.
Freeze unbaked: Press batter into prepared pan, wrap tightly, freeze up to 1 month. Bake from frozen at 350°F (175°C), adding 10–12 minutes.
To double: Multiply all ingredients by 2 except baking soda — use 1½ teaspoons only. Leavening does not scale linearly. Bake in two separate pans.
To halve: Use an 8x8 inch (20x20cm) pan. Reduce bake time to 18–22 minutes. All other ingredients halve linearly.
High altitude: Reduce baking soda by ¼ teaspoon, increase flour by 2 tablespoons, raise oven to 365°F (185°C). Start checking at 18 minutes.
Pro-tip: Refrigerate the fully cooled slab 30 minutes before cutting — bars slice cleanly with sharp edges rather than dragging or tearing.
Contains: Gluten, dairy, eggs. May contain traces of peanuts depending on chocolate chip brand — check packaging before serving to allergy-sensitive guests.