To chop chocolate for baking, set the bar on a clean, completely dry cutting board and use a long serrated knife. Start at one corner and press the blade down through the bar in thin diagonal strips, rocking the knife rather than sawing. Then turn the strips and cut across them until the pieces are the size your recipe needs: small and even for melting, rough chunks and shards for cookies.
Chopping a bar takes a few minutes longer than opening a bag of chips. The result is worth it. A chopped bar gives a mix of sizes, from fine flecks that melt into the dough to large chunks that stay as pools, and bar chocolate usually lacks the stabilizers that help chips keep their shape in the oven.
Start with a dry board
Water is the first thing to rule out. Ghirardelli’s guide to tempering and melting chocolate warns that even a drop of water or other liquid can cause chocolate to seize up, and advises that the work surface, pans and tools be absolutely dry before melting.
That matters most when the chopped chocolate is headed for a double boiler or the microwave. If the board was washed a few minutes earlier, wipe it dry with a clean towel, then let it air-dry a little longer. Dry the knife too.
The second thing to check is smell. Cocoa butter can absorb strong flavors such as garlic and coffee, according to Dandelion Chocolate’s storage guide. A board that has been used for onions or garlic should be washed well and fully dry before the chocolate goes on it. Keeping one board, or one side of a board, for sweet work avoids the problem; why a separate board for onions and garlic explains the habit.
Choose the knife
A serrated knife is the best tool for most chocolate. The teeth grip the smooth, hard surface of the bar instead of skidding off it. In King Arthur Baking’s comparison of tools for chopping chocolate, a serrated knife scored 10 out of 10, with a medium-serration bread knife the testers’ favorite, and a chef’s knife scored 5, partly because it sent pieces jumping around the board.
A heavy chef’s knife still works, especially on thin bars. If you use one, put your free hand flat on the spine near the tip and press straight down, so the edge pushes through the chocolate instead of sliding across it.
Using a bread knife on your board is fine as long as you press down rather than saw hard against the surface. A serrated bread knife on a bamboo board covers how to keep the board in good shape when you use one.
The corner method, step by step
- Unwrap the bar and set it flat on the board, smooth side up. If it is very cold and brittle from a cool pantry, let it sit at room temperature for a while so it cuts rather than shatters.
- Start at one corner. Set the knife across the corner at an angle and press down. A corner gives the edge a small point to bite into, so the blade is less likely to bounce off the flat face.
- Work in thin diagonal strips. Move the blade back a quarter inch or so and press down again, working across the bar from that corner. Rock the knife gently from tip to heel as you press. The chocolate will break into thin strips and shards.
- Turn and cut across. Gather the strips into a rough pile, turn the knife ninety degrees and chop across them to make smaller pieces.
- Gather with the blade. Use the flat of the knife, or a bench scraper, to sweep stray pieces back into the pile rather than your fingers. Warm hands soften chocolate and leave prints.
King Arthur’s testers held the bread knife high on the handle, close to the blade, and rested the edge of the handle on the board for control, rocking the knife through the chocolate instead of sawing.
How fine to chop
The right size depends on what the chocolate is for.
For melting. Small, even pieces. Ghirardelli recommends breaking or cutting chocolate into pieces about half an inch across for even melting. Mixed sizes melt unevenly, with large lumps still solid while small pieces are already hot.
For cookies and scones. Rough chunks between a quarter and three quarters of an inch, with all the shards and dust from the cutting left in. The fine pieces streak the dough; the large ones turn into pools.
For folding into batter or whipped cream. A fine, even chop, so the pieces stay suspended instead of sinking to the bottom.
For a garnish. Fine shavings, made by drawing the knife at a low angle across the edge of the bar, or by using a vegetable peeler along the long side of a slightly warmed bar.
Bars that have bloomed
Sometimes a bar has a dull, white or streaky surface. That is bloom. Dandelion Chocolate explains that sugar bloom forms when moisture dissolves sugar on the surface, which then recrystallizes as the water evaporates; white streaks are cocoa butter that separated after the chocolate melted and set again. Dandelion describes both as safe to eat and suggests baking with bloomed chocolate or melting it into brownies, where the look no longer matters.
To prevent it, store chocolate wrapped, in a cool, dry and dark cupboard, away from strong-smelling foods.
Other ways to chop
- A food processor chops fast but gives uneven pieces and a lot of fine dust. Pulse in short bursts, and use it for chocolate you plan to melt.
- A rolling pin works for rough pieces: keep the bar in its wrapper, put it in a bag and tap it. King Arthur notes that this method also creates small chocolate dust that disappears during baking.
- Breaking by hand works for chunky cookie pieces, though the sizes are uneven.
For the knife, nothing beats a long serrated blade. The same rocking technique works for nuts, which scatter in much the same way; how to chop nuts covers it.
Setting up the board
Chocolate shards travel. A board with room to spread out keeps them in one place. The WONAMU. bamboo cutting board is 12 by 9 inches, enough to chop a bar and push the pile to one side while you work on the next.
Put a damp towel under the board so it does not move when you press down. When you are finished, scrape any chocolate off the board with a bench scraper, wash it in hot, soapy water and dry it on its edge. If the chocolate is going into brownies, how to cut brownies and bars picks up where this leaves off.
The short version
Use a clean, completely dry board free of onion or garlic smells. Set the bar flat and chop from one corner with a long serrated knife, pressing and rocking in thin diagonal strips. Turn the strips and chop across.
Cut about half an inch for melting, leave rough chunks and shards for cookies, and chop fine for folding into batter. Gather the pieces with the blade or a bench scraper, not your warm hands.
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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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