To cut brownies and bars into clean squares, let them cool completely, lift the whole slab out of the pan with a parchment sling, and set it on a cutting board. Use a long, sharp knife dipped in hot water and wiped dry before every cut, and press straight down in one motion rather than sawing. Cut the slab in half, then each half in half again, so every square comes out the same size. The edges stay sharp and the tops stay smooth.

Warm brownies crumble and drag. Cutting inside the pan crushes the corners and scratches the metal. Each step below takes care of one of those problems.

Line the pan with a sling

The clean cut starts before baking. Line the pan with a strip of parchment paper that runs across the bottom and up two opposite sides, with a few inches of overhang on each side. For an 8-inch or 9-inch square pan, a strip about 8 inches wide and 16 inches long does it. A second strip at right angles lines the other two sides.

The overhanging paper forms handles. When the brownies have cooled, you lift the whole slab out in one piece instead of digging squares out of the corners.

Grease the pan lightly before laying in the parchment so it sticks to the pan and does not shift when you pour in the batter.

Let them cool completely

This is the step most people skip, and it decides everything else. Fresh from the oven, the inside of a brownie is still setting. Cut it warm and the knife drags soft crumbs through the slab and smears the top.

  • Cool brownies and blondies in the pan on a rack for at least one hour, better two.
  • Fudgy brownies, cheesecake bars and anything with a soft layer cut even more cleanly after an hour or two in the refrigerator.
  • Lemon bars and other custard bars should always be chilled before cutting.

A firm, cool slab gives a clean edge. If you need them faster, cool them for 30 minutes at room temperature and then 30 minutes in the refrigerator.

Lift the slab onto a board

Run a thin knife or offset spatula around the two unlined sides of the pan to free any edges that stuck. Then pull up on the parchment handles and lift the slab straight out. Set it on a cutting board and slide the parchment out from underneath, or leave it there and cut through it.

Now the knife can reach the full depth of the slab at the right angle. In the pan, the walls get in the way, and the corner pieces always come out ragged.

Choose the right knife

A long, sharp chef’s knife with a straight edge is the best tool for most bars. It is long enough to cut across an 8-inch or 9-inch slab in one press, and the smooth edge leaves a clean face. A serrated knife works for bars with a crisp crust or a crunchy topping, like a streusel, but it can leave ridges on fudgy brownies.

A bench scraper is another good option for soft, dense bars: press it straight down in one motion.

The hot knife method

  1. Fill a tall glass or pitcher with very hot water and stand the knife in it for a minute.
  2. Wipe the blade dry with a clean towel.
  3. Press the knife straight down through the slab in one firm motion, from tip to heel, rather than sawing back and forth.
  4. Pull the knife straight out toward you, or lift it straight up.
  5. Wipe the blade clean and dip it in the hot water again before the next cut.

The warm blade melts a thin line through the chocolate and fat instead of dragging crumbs, and wiping it between cuts means each cut starts with a clean edge.

Cut in halves for even squares

Measuring each square by eye produces a row that gets smaller as you go. Halving keeps them even.

  1. Cut the slab in half.
  2. Cut each half in half again. You now have four equal strips.
  3. Cut each strip in half, or in thirds, depending on the size you want.
  4. Turn the board 90 degrees and repeat across the strips.

For an 8-inch pan, cutting each direction into four gives sixteen 2-inch squares. Cutting each direction into five gives twenty-five smaller pieces for a party platter. A ruler laid along the edge helps if you want them exact.

Trim the outer edges first if you want every square to look identical. The trimmings are the cook’s share.

Bars that need extra care

  • Lemon bars: chill thoroughly and dust with powdered sugar only after cutting, or the sugar dissolves into the cut faces.
  • Cheesecake bars: chill overnight, and wipe the knife after every cut without fail.
  • Rice cereal treats: grease the knife lightly instead of heating it.
  • Bars with a nut or oat topping: use a serrated knife and a gentle sawing motion through the topping, then press down through the rest.
  • Fudge and toffee: the same principles apply, with a well-chilled slab and a warm, dry knife.

A good surface for cutting

Cutting bars on a cutting board, instead of in the pan, protects the pan’s finish and lets the knife go all the way through. A wooden or bamboo board also yields slightly under the blade, unlike glass or stone, which meets the edge with a hard stop.

The WONAMU. bamboo cutting board is 12 by 9 inches, enough to hold a full 9-inch slab with room to work around it. Brownies can go straight from the board to the table, much like other foods served on a cutting board. Wash it with warm soapy water afterward and dry it on edge.

The short version

Line the pan with a parchment sling. Cool brownies and bars completely, chilling fudgy or custard bars too. Lift the slab out onto a board. Use a long, straight knife dipped in hot water and wiped dry before every cut, press straight down, and cut in halves, then halves again, for even squares.

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WONAMU. makes a bamboo cutting board designed for daily prep, 12 × 9 inches, bamboo, with a perimeter juice groove. Available on Amazon.

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