How to Make Christmas Crack

This moves fast once the toffee comes off the heat, so have it all on the counter before you start.

One and a half sleeves of saltines, 1 1/4 cups butter, 1 cup light brown sugar, a 12 oz bag of milk chocolate chips, and sprinkles or chopped nuts for the top.

Heat the oven to 350F now. There is a five-minute bake in the middle of this and you do not want to be waiting on a cold oven with hot toffee going firm in the pan.

Spray a rimmed baking sheet generously with nonstick spray, right into the corners.

Lay the saltines out in a single layer, salt side up, butted edge to edge. Break a few in half to fill the gaps at the ends. You want the base covered.

Bare pan is where the toffee runs underneath and welds itself down, which turns getting the finished sheet out into a fight.

Put the butter and brown sugar in a saucepan over medium heat.

Use a bigger pan than seems necessary. The mixture climbs the sides once it comes to a boil, and a small pan means it goes over.

Whisk as the butter melts so the sugar disperses instead of sitting in a layer on the bottom, where it scorches.

Bring it to a proper rolling boil, then set a timer for two minutes and keep whisking the whole time.

This one number decides whether you get toffee or sweet butter sauce. Under two minutes and it never sets firm. Well over and it goes grainy and the butter splits out.

Do not stop whisking. The sugar catches on the base of the pan within seconds and burnt sugar taints the whole batch.

Take the pan off the heat and pour straight over the crackers.

Work in lines back and forth across the tray rather than emptying it in one spot. That single change leaves you far less spreading to do, and spreading is where it starts to set on you.

It is thin and runs quickly while hot, so pour now and tidy after.

Spread the toffee out with an offset spatula until every cracker is coated, pushing it right into the corners.

Any cracker left bare comes out of the oven as a plain dry cracker in the middle of the batch, and it is always the piece someone picks up.

It does not have to be even. It has to be complete.

Into the 350F oven for about five minutes.

You are waiting for the whole surface to bubble. That is the toffee soaking down into the crackers, which is what turns them from dry crisp into the chewy-crisp layer that makes this work.

Pull it out once it is bubbling evenly all over rather than just at the edges. If a cracker has slid out of line, nudge it straight with a knife now while everything is still soft.

Straight out of the oven, scatter the whole bag of chocolate chips over the top.

Do not melt them separately. The heat already in the toffee does the entire job, and separately melted chocolate sits on top as a distinct layer that cracks off later instead of bonding.

Spread them out reasonably evenly, then leave it alone for two or three minutes. They will slump and turn glossy on their own.

Once the chips have gone glossy, spread them flat with the offset spatula and take the chocolate right to the edges.

If they have not softened enough, slide the pan back into the warm oven for a minute and try again.

Add sprinkles while the chocolate is still tacky, or they will not stick. Soft sprinkles work better than hard nonpareils, which fight the snap of the toffee underneath. Chopped pecans or walnuts are the other classic finish.

Cool at room temperature first, then move the tray to the fridge for about twenty minutes to set the chocolate hard.

Slide a knife underneath and lift. The whole sheet comes up and cracks apart, which is where the name comes from. Break the rest by hand.

Uneven shards are the point. Nobody wants a neat square of this.

It keeps in an airtight tin in the fridge for a couple of weeks and bags up well for gifting to neighbours and teachers.