This nut-free English toffee is crisp and buttery with a layer of semisweet chocolate on top. It's naturally gluten free and easy enough for your first batch of homemade candy.
Line a jelly roll pan with a silicone baking mat or parchment paper. Chop the chocolate if you're using a bar.
Add the butter, sugar, water, and salt to a heavy pot over medium heat. Stir gently until the butter melts and everything combines.
1 cup unsalted butter, 1 cup sugar, 1/4 cup water, 1/2 teaspoon salt
Once it boils, clip on a candy thermometer. Stir slowly and gently now and then, keep the heat at medium, and leave any sugar crystals on the sides of the pot alone.
Take the pot off the heat when the thermometer reads about 295 degrees. The toffee climbs to 300 degrees on its own.
Pour the toffee onto the lined pan and spread it to the edges with a spatula.
Wait about a minute, then score the toffee into about 30 pieces with a pizza wheel, pressing in lines without cutting through.
Scatter the chocolate over the hot toffee. Let it melt for a few minutes, then spread it to the edges with a clean spatula. Sprinkle with flaky salt if you like.
6 ounces chocolate
Let the chocolate set at room temperature for an hour. Don't refrigerate it. Break the toffee along the score lines.
Store in a sealed container on the counter for up to two weeks, then freeze the broken pieces.
Use chocolate callets or a chopped block of good chocolate instead of chips, which don't melt as smoothly. Semisweet, dark, and milk chocolate all work.
Keep the heat at medium. If the butter and sugar get too hot before they melt together, the butter separates into an oily layer, and the chocolate won't stick.
If the chocolate won't melt all the way, put the pan in the oven on the proof setting (about 110 degrees) for five minutes. If your oven doesn't have a proof setting, preheat it to its lowest temperature for five minutes, turn it off, and put the pan inside.