Toll House Marble Squares

The marble squares trick has been hiding in plain sight on the back of chocolate chip packages since the 1950s, and it’s one of the smartest cookie-bar shortcuts in American baking. Instead of folding chips into the dough (which keeps them as discrete morsels), scatter them on top, hit them with a quick minute of oven heat to soften, then drag a knife through to streak the chocolate into ribbons.

The result is a blondie that looks fancy and tastes like every bite has chocolate without ever crossing into chocolate-cookie territory. The base is straight Toll House dough, with both white and brown sugar for chew and depth.

Don’t over-marbleize. Two or three drags of a knife is enough to create swirls. More turns the whole pan into a muddy brown blondie.

Watch the bake. Twelve to fourteen minutes is the window. The bars firm up as they cool, so pull them when the edges set and the center still looks slightly underdone.

Pro Tips

• Toast the nuts first for a richer, less raw flavor. Walnuts and pecans both work.
• Use semi-sweet chips, not milk chocolate. Milk chocolate melts to a sweeter, less defined ribbon.
• Line the pan with parchment with overhang for easy lift-out. Cleaner squares, no scraping.
• Cool completely before cutting. Warm bars tear and the chocolate smears.

Variations

• Add a teaspoon of espresso powder to the dough for deeper chocolate flavor.
• Swap half the chips for white chocolate or peanut butter chips for a tri-colored marble.
• Sprinkle flaky sea salt over the warm tops for a salted-blondie finish.